IRLF 


SB    Efi 


LIBRARY 
UNIVERSITY  OF  CALIFORNIA 

ST.    LOUIS  EXHIBIT 


LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


OF" 


Class 


MINEKAL    TABLES 

FOR   THE    DETERMINATION   OF   MINERALS    BY 
THEIR    PHYSICAL    PROPERTIES. 


BY 

ARTHUE  S.   EAKLE,  Pn.D., 

Assistant  Professor  of  Mineralogy,  University  of  California, 


FIRST  EDITION. 
FIRST  THOUSAND. 


NEW  YORK : 

JOHN  WILEY   &   SONS. 

LONDON:   CHAPMAN  &  HALL,   LIMITED. 

1904. 


Copyright,  1904, 

BY 

ARTHUR   S.    EAKLE. 


ROBERT  DRTJMMOND,  PRINTER,  NEW  YORK. 


INTRODUCTION. 


THE  natural  method  of  identifying  minerals  is  by  using  those  charac- 
ters which  are  prominent  or  which  can  be  determined  in  the  field  or 
laboratory  in  the  simplest  manner.  Practice  in  the  determination  of 
minerals  by  their  physical  properties  tends  to  develop  the  habit  of 
close  and  careful  observation,  and  at  the  same  time  enables  the  student 
to  acquire  more  knowledge  of  minerals  in  a  given  time  than  could  be 
obtained  by  any  other  method.  Experience  has  demonstrated  that 
work  in  blowpipe  analysis  is  less  apt  to  become  merely  mechanical  if 
it  has  been  preceded  by  such  practice. 

The  tables  include  the  common  minerals  and  a  few  others  of  local 
prominence,  which  are  generally  considered  as  rare  in  occurrence.  The 
minerals  are  arranged  primarily  according  to  streak  and  color,  as  seen 
in  the  Analytical  Key.  and  under  each  color  the  arrangement  is  accord- 
ing to  hardness.  The  tables  differ  from  those  of  Weisbach  chiefly  in 
disregarding  luster  as  an  important  division  and  in  maintaining  the 
same  system  of  arrangement  throughout.  Various  works  on  mineralogy, 
especially  Dana's  System  of  Mineralogy,  have  been  consulted  in  the 
preparation  of  the  tables.  For  valuable  suggestions  and  criticisms  the 
author  is  especially  indebted  to  Professor  Charles  Palache  of  Harvard, 
who  used  the  manuscript  copies  of  the  tables  in  the  Summer  School  of 
the  University  of  California. 

BERKELEY,  August  25,  1903. 

iii 


119593 


MINERAL  TABLES. 

/  •  •  •  - 

UNIVERSITY 

PHYSICAL   PROPERTIES. 

THE  only  apparatus  needed  for  the  tables  is  a  pocket-knife,  a  horse- 
shoe magnet,  a  pocket-lens,  a  piece  of  unglazed  porcelain  or  streak-plate, 
and  a  scale  of  hardness  consisting  of  nine  minerals.  This  scale  can  be 
procured  of  any  mineral  dealer  or  can  be  made  up  from  specimens  in 
an  ordinary  collection  of  minerals. 

Color. — The  color  of  a  mineral  is  perhaps  the  most  important  property 
used  in  its  identification,  yet  it  is  the  most  difficult  to  accurately 
describe.  A  mineral  may  have  but  one  characteristic  color,  or  it 
may  occur  in  various  colors  and  shades ;  consequently  a  mineral  may 
be  repeated  several  times  in  the  tables.  The  color  must  always  be 
judged  by  the  fresh  surface  or  fracture,  and  it  should  be  homogeneous 
throughout  the  mineral.  Vitreous  minerals  may  often  be  discolored 
or  stained  by  impurities,  when  they  manifestly  belong  to  the  color- 
less or  white  class. 

Luster. — The  luster  of  a  mineral  refers  to  the  kind  of  reflected  surface. 
The  common  kinds  are:  metallic;  submetallic=  imperfect  metallic; 
vitreous  =  glassy;  adamantine  =  brilliant  oily  luster;  resinvus;  greasy; 
pearly;  silky;  waxy. 


2  MINERAL   TABLES. 

Streak. — The  streak  of  a  mineral  is  the  color  of  its  fine  powder.  It  is 
best  obtained  by  rubbing  the  specimen  upon  the  streak-plate  until  a 
definite  color  is  produced. 

Hardness. — By  hardness  is  meant  the  resistance  that  a  mineral  offers 
to  abrasion  or  scratching.  The  relative  hardness  of  a  mineral  is 
usually  determined  by  scratching  it  successively  by  minerals  or  sub- 
stances of  known  hardness,  two  minerals  of  the  same  hardness 
mutually  scratching  each  other.  The  scale  of  hardness  in  common 
use,  called  the  Moh's  scale,  in  ascending  degree  of  hardness,  is  as 
follows:  1,  Talc;  2,  Gypsum;  3,  Calcite;  4,  Fluorite;  5,  Apatite; 
6,  Feldspar;  7,  Quartz;  8,  Topaz;  9,  Corundum;  10,  Diamond. 

The  thumb-nail  will  scratch  minerals  up  to  2J,  and  the  ordinary 
laiife-blade  up  to  5J  in  the  scale;  with  a  little  practice  the  relative 
hardness  of  a  mineral  under  6  can  be  approximately  determined  with 
a  knife-blade.  Above  6  the  scale  of  hardness  is  necessary.  The 
relative  hardness  of  many  of  the  metallic  or  submetallic  minerals 
can  often  be  judged  by  the  ease  or  difficulty  in  obtaining  a  streak 
on  the  streak-plate.  Fine  fibrous  and  fine  granular  minerals  usually 
appear  to  be  much  softer  than  the  individual  fiber  or  grain  would 
be,  if  it  were  coarser.  Also  the  surface  of  some  minerals  is  often 
much  softer  than  the  fresh  interior,  owing  to  alteration. 

Specific  Gravity. — The  gravity  of  a  mineral  is  its  weight  compared  with 
the  weight  of  an  equal  volume  of  water.  It  is  determined  by  first 
weighing  the  mineral  in  air  and  then  weighing  it  suspended  in  water. 

w 
If  w=  weight  in  air,  and  i</  =  weight  in  water,  then  G=  — — — ,.     The 

gravity  of  minerals  can  be  determined  with  a  chemical  balance  or 


PHYSICAL  PROPERTIES  * 

with  the  convenient  Jolly  spring-balance.  Whether  the  mineral  is 
light,  medium,  heavy,  or  very  heavy  can  often  be  judged  simply  by 
hefting  it. 

Crystallization. — A  few  mineral  substances  on  assuming  a  solid  condition 
do  not  crystallize  and  are  said  to  be  amorphous,  but  most  mineral 
substances  when  solidifying  have  the  property  of  crystallizing  into 
certain  definite  crystal  forms,  and  any  such  crystalline  substance 
must  belong  to  one  of  six  different  crystal  systems.  These  systems 
are:  1,  Isometric;  2,  Tetragonal;  3,  Hexagonal;  4,  Orthorhombic; 
5,  Monoclinic;  6,  Triclinic. 

Assuming  that  each  system  has  axes  which  are  intersected  by  the 
crystal  planes,  then: 

1.  Isometric  has  three  equal  axes  all  at  right  angles.     The  com- 
mon forms  in  this  system  are:  Cube,  having  six  square  faces; 
Octahedron,  having  eight  equilateral  triangular  faces;  Rhombic 
dodecahedron,  having  twelve  rhombic  faces ;  Icosatetrahedron  or 
Trapezohedron,    having    twenty-four    trapezohedral     faces; 
Tetrahedron,  having  four  equilateral  triangular  faces;  Pentag- 
onal dodecahedron  or  Pyritohedron,  having  twelve  pentagonal 
faces. 

2.  Tetragonal  has  two  horizontal  axes  equal,  and  one  vertical 
longer  or  shorter  than  these,  all  at  right  angles.     The  common 
forms  are:  Prisms,  faces  intersecting  one  or  both  horizontal 
axes,  and  parallel  to  the  vertical;  Pyramids,  faces  intersect- 
ing  the  vertical  and   one    or  both  horizontal  axes;   Basal 
pinacoids,  faces  intersecting  the  vertical  and  parallel  to  the 
horizontal  axes. 


MINERAL  TABLES. 

3.  Hexagonal  has  three  horizontal  axes  equal  and  making  angles 

of  60°  with  each  other,  and  one  vertical,  longer  or  shorter  than 
these,  and  at  right  angles  to  them.  The  common  forms  are: 
Prisms,  faces  intersecting  two  or  three  of  the  horizontal  axes 
and  parallel  to  the  vertical;  Pyramids,  faces  intersecting  the 
vertical  and  two  or  three  of  the  horizontal;  Basal  pinacoids, 
faces  intersecting  the  vertical  and  parallel  to  the  horizontal; 
Rhombohedrons,  solids  of  six  oblique  rhombic  faces;  Scaleno- 
hedrons,  solids  of  twelve  scalene-triangular  faces. 

4.  Orthorhombic  has  three  unequal  axes  all  at  right  angles :  a  short 
forward-and-back  horizontal  axis,  the  brachyaxis;    a  long 
right-and-left  horizontal  axis,  the  macroaxis;  and  a  vertical 
axis.     The  common  forms  are :  Prisms,  faces  intersecting  the 
horizontal  axes  and  parallel  to  the  vertical;  Pyramids,  face? 
intersecting  the  three  axes;   Macropinacoids,  faces  intersect- 
ing the  brachyaxis  and  parallel  to  the  other  two;   Brachy- 
pinacoids,  faces  intersecting  the  macroaxis  and  parallel  to  the 
other  two;    Macrodomes,  faces   intersecting   the  brachyaxis 
and  the  vertical  and  parallel  to  the  macroaxis;  Brachydomes, 
faces  intersecting  the  macroaxis  and  the  vertical  and  parallel 
to  the  brachyaxis;    Basal  pinacoids,  faces  intersecting  the 
vertical  and  parallel  to  the  horizontal  axes. 

5.  Monodinich&s  three  unequal  axes:  a  forward-and-back  inclined 

axis,  the  clinoaxis;  a  right-and-left  horizontal  axis,  the  ortho- 
axis;  and  a  vertical  axis.  The  common  forms  are:  Prisms, 
faces  intersecting  the  two  lateral  axes  and  parallel  to  the 
vertical;  Pyramids,  faces  intersecting  all  three  axes;  Ortho- 


PHYSICAL  PROPERTIES  & 

pinacoids,  faces  intersecting  the  clinoaxis  and  parallel  to  the 
other  two;    Clinopinacoids,  faces  intersecting  the  orthoaxis 
and  parallel  to  the  other  two;  Orthodomes,  faces  intersecting 
the  clinoaxis  and  the  vertical  and  parallel  to  the  orthoaxis; 
Clinodomes,  faces  intersecting  the  orthoaxis  and  the  vertical 
and  parallel  to  the  clinoaxis;  Basal  pinacoids,  faces  intersect- 
ing the  vertical  and  parallel  to  the  other  two. 
6.  Tridinic  has  three  unequal  axes,  all  oblique  to  each  other. 
The  common  forms  are  the  same  as  in  the  orthorhombic 
system,  namely,  Prisms;  Pyramids;  Macropinacoids;  Brachy- 
pinacoids;  Macrodomes;  Brachydomes;  Basal  pinacoids. 
Twinning. — Some  crystals  instead  of  being  simple  individuals  are  made 
up  of  two  crystals,  not  in  parallel  position,  but  united  along  a  plane 
common  to  both,  and  such  crystals  are  said  to  be  twinned.     Twinning 
is  usually  indicated  by  reentrant  angles  between  the  faces. 
Cleavage. — The  property  which  a  mineral  has  of  splitting  or  breaking 
along  certain  definite  directions  is  called  cleavage.     The  cleavage  is 
always  parallel  to  a  possible  crystal  plane,  and  the  kind  of  cleavage 
is  designated  by  the  name  of  the  plane  to  which  it  corresponds  in 
direction.    The  common  kinds  of  cleavage  for  each  system  are: 
Isometric,  cubic,  octahedral,  and  dodecahedral. 
Tetragonal,  basal  and  prismatic. 
Hexagonal,  basal,  prismatic,  and  rhombohedral. 
Orthorhombic,  basal;  prismatic;  macro-  or  brachypinacoidal. 
Monoclinic,  basal;  prismatic;  ortho-  or  clinopinacoidal. 
Tridinic,  basal  and  macro-  or  brachypinacoidal. 
The  direction  of  cleavage  can  usually  be  determined  only  on  the- 


6  MINERAL  TABLES. 

actual  crystal  and  not  on  the  average  massive  mineral  specimen. 
Bright,  smooth  cleavage  faces  are,  however,  usually  present  on 
specimens  of  minerals  which  possess  good  cleavage,  and  often  they 
are  very  prominent. 

Fracture. — When  the  direction  of  breakage  is  not  definite,  but  occurs  in 
any  way  irrespective  of  crystal  planes,  the  mineral  fractures.     The 
fracture  may  be  even;  uneven;   rough;   conchoidal  =  rounded,  shell- 
like;  splintery;  these  terms  referring  to  the  kind  of  surface. 
Tenacity. — The  terms  used  to  denote  the  tenacity  are: 

Malleable,  when  the  mineral  can  be  flattened  by  hammering. 
Sectile,  when  it  can  be  cut  with  a  knife  but  will  break  in  pieces 

by  hammering. 

Brittle,  when  it  will  break  in  pieces  by  hammering. 
Tough,  when  it  is  difficult  to  break  by  hammering. 
Structure. — Most  minerals  do  not  occur  as  simple  individual  crystals  in 
nature,  but  rather  as  aggregates  of  imperfectly  formed  crystals,  or 
simply  as  crystalline  masses.     Some  of  the  terms  used  to  describe 
the  structure  of  specimens  are : 

Massive,  when  the  specimen  has  an  irregular,  indefinite  shape. 

It  may  be  fine  or  coarse  granular. 

Crypto-crystalline,   extremely  fine    crystalline;    impalpable  =  ex- 
tremely dense,  compact. 
Fibrous,  composed  of  fibers.    The  fibers  may  be  parallel,  radiate, 

or  divergent  in  any  direction. 
Columnar,  stout  fibrous,  forming  columns. 
Capillary,  hair-like  fibers. 
AcicuJar,  needle-like. 


PHYSICAL  PROPERTIES.  7 

• 

Reticulated,  when  the  fibers  cross  each  other,  forming  a  net-like 

structure. 

Mammillary,  large  rounded  surfaces. 
Reniform,  kidney-shaped  masses. 

Botryoidal,  grape-like  structure  or  small  rounded  surfaces. 
Geodal,  cavities  lined  with  crystals. 
Drusy,    rough    surfaces   due     to    innumerable    small    imperfect 

crystals. 

Micaceous,  thin  sheets  or  scales,  like  mica. 
Lamellar,  thin  plates. 
Foliated,  thin  leaves. 

Other  terms  are  used  to  describe  the  structures  of  mineral  speci- 
mens, but  their  meaning  in  general  is  self-evident. 


ANALYTICAL  KEY. 


1.  STREAK  DARK  GRAY  OR  IRON-BLACK: 

Color:  Dark  Gray  or  Black 10-12 

Metallic  White  to  Light  Metallic  Gray 12-14 

Brass;  Bronze;  Copper-red  or  Brown 14-16 

2.  STREAK  METALLIC  WHITE  TO  LEAD- OR  STEEL-GRAY:  « 

Color:  Metallic  White  or  Light  Metallic  Gray 16 

3.  STREAK  RED   OR  RED-BROWN: 

Color :  Red  or  Brown , 18 

Dark  Gray  or  Black 20-22 

4.  STREAK  YELLOW  OR  YELLOW-BROWN: 

Color:  Red 22 

Yellow 22-24 

Brown  or  Black 24-26 

Green 26 

5.  STREAK  BLUE  OR  GREEN: 

• 

Color:  Blue,  Green,  or  Black 26-28 

6.  STREAK  UNCOLORED,  WHITE  OR  LIGHT  GRAY  : 

Color:  Yellow  or  Brown 28-38 

Pink,  Red,  or  Red-violet 38-44 

Blue  or  Blue-violet 44-46 

Green 46-54 

Black 54-50 

White,  Gray,  or  Colorless 56-68 

9 


10 


STREAE  DARK  GRAY 


Name. 

Composition. 

Color. 

Streak. 

Luster.          H. 

GRAPHITE 

c 

Dark  steel- 

Black 

Metallic 

1.2 

gray 

Dark  sil- 

Dull 

Iron-black 

ver-gray 

MOLYBDENITE 

MoS2 

Bluish  lead- 
gray 

Lead-gray 
Sometimes 

Metallic 

1 
1.5 

* 

greenish 

PYROLUSITE 

MnO2 

Black 

Dull  black 

Metallic 

2 

Blackish 

Dull 

gray 

STIBNITE 

Sb^g 

Dark  lead- 

Dark  lead- 

Metallic 

2 

s 

gray 

Black 

5 

M 

« 

o 

JAMESONITE 

Pb2Sb2S5 

Dark  lead- 

Grayish 

Metallic 

2 

>< 

gray 

black 

3 

S 

§ 

ARGENTITE 

Ag2S 

Dark  lead- 

Dark  lead- 

Metallic 

2 

A 

Black 

gray 

2.5 

H 

tf 

STEPH^NITE 

Ag5SbS4 

Iron-black 

Iron-black 

Metallic 

2 

S 

.0 

o 

D 

GALENITE 

PbS 

Dark  lead- 

Grayish 

Metallic 

2.5 

gray 

black 

3 

Dark  lead- 

gray 

CHALCOCITE 

(XS          ,         . 

Dark  lead- 
or  steel- 

Bglack 

Dark  gray 

Metallic 

2.5 
3 

ENARGITE 

Cu3AsS4 

Grayish 
black 

Grayish 
black 

Metallic 

3 

OR  IRON-BLACK. 


11 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  basal,  perfect 
in    crystallized 
masses;  sectile; 
flexible 

2.2 

Foliated  ;  scaly  ;  mas- 
sive; granular;  earthy 

Feels  greasy  ;  plates 
highly  flexible;  inelastic; 
occurs  with  calcite:  darker 
than  molybdenite 

Hex. 

C,  basal,  very  prom- 
inent ;     sectile  ; 
flexible 

4.7 

Foliated  ;     massive  ; 
scaly;  flaky 

Soft  and  greasy  like 
graphite  but  lighter  col- 
ored; usually  as  flakes  in 
quartz 

Orth. 

C,  none 
Brittle 

4.8 

Fibrous;      acicular;  !     Blackens    fingers;    often 
columnar;         earthy;    with  psilomelane;     darker 
powder                             than  stibnite 

Orth. 

C,  brachypinacoid- 
al,  perfect  and 
prominent 
Brittle  ;  slightly  sec- 
tile 

4.5 

Fibrous;   columnar; 
bladed;   prismatic 

Prisms  often  bent  and 
with  long  shining  cleavage 
faces;  sometimes  iridescent 

Orth. 

C,  basal,  prominent 
Brittle 

5.5 
6 

Acicular;       fibrous; 
capillary 

Resembles  stibnite,  but  is 
heavier  and  has  cleavage 
faces  transverse  to  length 

Isom. 

C,  not  important 
F,  hackly 
Slightly    malleable 

7.3 

^f? 

Octahedrons;  hack- 
ly masses  ;  arborescent  ; 
reticulated 

Resembles  tarnished  sil- 
ver; often  with  silver,  cop- 
per, barite;  cuts  like  lead 

Orth. 

C,  imperfect 
F,  uneven 
Very  brittle 

6.3 

Compact  ;    massive  ; 
crystals,  short  prisms 

Often  with  other  silver 
ores;  also  barite,  quartz, 
galena 

Isom. 

C,  cubic,  perfect 
and  prominent 
Sectile  to  brittle 

7.5 

Cubes;  cubo-octahe- 
drons;  granular;  foli- 
ated 

Often  with  sphalerite, 
pyrite,  tetrahedrite,  cerus- 
site,  anglesite,  dolomite, 
calcite,  fluorite  ;  heavier 
than  stibnite  and  never 
long  prismatic 

Orth. 

C,  indistinct 
F,    conchoidal     or 
granular 
Sectile 

5.7 

Compact;    massive; 
crystals   with   deeply 
striated  faces 

Often  coated  with  mala- 
chite; occurs  with  bornite, 
chalcopyrite,  quartz,  mala- 
chite, enargite 

Orth. 

C,   prismatic    and 
prominent 
Brittle 

4.4 

Massive 

Often  with  chalcocite, 
bornite,  famatinite 

12 


STREAK  DARK  GRAY 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

t 

TETRAHEDRITE 

Cu8Sb2S7 

Dark  lead- 

Dark  gray 

Metallic 

3 

TENNANTITE 

Cu8As2S7 

or  steel- 

4.5 

gray 

IRON 

Fe 

Steel-gray 

Black 

Metallic 

4 

w 

Black 

5 

o 

< 

4 
W 

PSILOMELANE 

MnO,H2O 

Grayish 
black 

Brownish 
black 

Submetallic 

5 
6 

g 

Dull  black 

>< 

<J 
Pi 

ILMENITE 

(FeTi)203 

Iron-black 

Brownish 

Metallic 

5.5 

s 

(Menaccanite) 

black 

6 

M 

3 

MAGNETITE 

Fe304 

Iron-black 

Iron-black 

Metallic 

5.5 

a 

6.0 

« 

S 

8 

FRANKLINITE 

(Fe,Mn,Zn)30, 

Iron-black 

Brownish 
black 

Metallic 

5.5 
6.5 

COLUMBITE 

(Fe,Mn)(Nb,Ta)2O6 

Pitch- 
black 

Grayish 
black 

Submetallic 
Vitreous 

6 

STIBNITE 

Sb^s 

Light  lead- 

Dark  lead- 

Metallic 

2 

H 

a  . 

gray 

gray 
Black 

it* 

2« 

GALENITE 

PbS 

Lead-gray 

Dark  lead- 

Metallic 

2.5 

3o 

Black 

:> 

1 

ANTIMONY 

Sb 

Light  steel- 

Lead-gray 

Metallic 

3 

l= 

gray 
Tin-  white 

3.5 

Q-O 

S" 

ARSENIC 

As 

Light  steel- 

Dark  gray 

Metallic 

3.5 

8 

gray 

OR  IRON-BLAC#. 


13 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Isom 

C,  none 
F,  granular 
Brittle 

4.4 
5.1 

Compact  ;  massive  ; 
tetrahedral  crystals 

Often  in  quartz  with 
galena,  chalcopyrite,  sphal- 
erite ;  sometimes  with 
very  brilliant  luster 

Isom. 

C,  not  important 
F,  hackly 
Malleable 

7.3 

7.8 

Massive 

Meteorites  often  have 
pitted  and  fused  surfaces 

None 

C,  none 
F,  conchoidal    and 
prominent 
Tough  to  brittle 

3.7 

4.7 

Impalpable  ;  massive  ; 
stalactitic  ;  botryoid- 
al;  rounded  masses 

Often  with  limonite,  py- 
rolusite,  manganite 

Hex 

C,  none 
F,  conchoidal 
Brittle 

4.5 
5 

Grains  and  pebbles; 
black  sand  ;  platy  ; 
massive  granular. 

Slightly  magnetic  to  non- 
magnetic 

Isom. 

C,  not  prominent 
F,  uneven 
Brittle 

5.2 

Octahedrons;  mas- 
sive granular  to  com- 
pact; sand 

Strongly  magnetic  ;  often 
with  quartz,  feldspar, 
hornblende,  chlorite;  crys- 
tals usually  very  perfect 

Isom. 

C,  none 
F,  uneven 
Very  brittle 

5.2 

Octahedrons,  usu- 
ally rounded;  granu- 
lar; massive 

Usually  with  zincite,  wil- 
lemite,  rhodonite,  and  cal- 
cite;  magnetic,  but  not 
strongly  like  magnetite 

Orth 

C,  not  important 
F,  uneven 
Brittle 

5.3 
7.3 

Crystals,  usually  in 
parallel  groups 

Occurs  in  granite,  often 
with  albite,  tourmaline, 
beryl 

Orth. 

C,  brachypinacoidal 
very  prominent 
Brittle  ;  slightly  sec- 
tile 

4.5 

Prismatic  ;  fibrous  ; 
columnar;  bladed 

Often  in  ouartz  with 
galenite,  sphalerite,  tetra- 
hedrite 

Isom, 

C,  cubic,  perfect  and 
prominent 
Sectile  to  brittle 

7.5 

Cubes  ;  cubo-octa- 
hedrons;  granular;  fo- 
liated; massive 

Much  heavier  than  stib- 
nite  and  never  long  pris- 
matic 

Hex. 

C,  basal,  prominent 
Brittle 

6.7 

Massive;  lamellar 

Often  with  stibnite;  usu- 
ally coated  with  earthy 
white  oxide  of  antimony 

Hex. 

C,  basal,  not  usually 
prominent 
F,  granular 
Brittle 

6 

Rounded,  renifonn 
masses;  granular 

Usually  tarnished  dull 
black  on  surface 

14 


STREAK  DARK  GRAY 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

COLOR  METALLIC  WHITE 
TO  LIGHT  GRAY. 

ARSENOPYRITE 

FeAsS 

Light  steel- 
gray 
Tin-  white, 
often  with 
brassy  or 
reddish 
tinge 

Grayish 
black 

Metallic 

5.5 
6 

SMALTITE 
CHLOANTHITE 

Co  As, 

NiAs2 

Tin-white 
Light  steel- 
gray 

Grayish 
black 

Metallic 

0.0 

0 

COBALTITE 

CoAsS 

Silver- 
white  with 
usually 
copper- 
red  tinge 

Grayish 
black 

Metallic 

5.5 

MARCASITE 

FeS2 

Brassy 
steel-gray 
Pale  brass- 
yellow 

Greenish 
black 
Brownish 
black 

Metallic 

6 
6.5 

^/VJ-iUK  BKABBL  BROXVZB,  COFFER-RED, 
OR  BROWN. 

BOROTTE 

Cu3FeS3 

Copper- 
brown 
Horseflesh- 
brown 

Grayish 
black 

Metallic 

3 

ENARGITE 
FAMATINITE 

Cu3AsS4 
Cu3SbS4 

Reddish 
brown 
Bronze- 
brown 

Grayish 
black 

Metallic 

3 

MlLLERITE 

NiS 

Brass-yel- 
low 

Greenish 
black 

Metallic 

3 
3.5 

CHALCOPYRITE 

CuFeS2 

Deep 
brass- 
yellow 

Greenish 
black 

Metallic 

3.5 
4 

PYRRHOTITE 

Fe7S8  to  FeuS12 

Bronze- 
yellow 
Bronze- 
brown 

Grayish 
black 

Metallic 

3.5 
4.5 

OR  IRON-BLACK. 


15 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  not  prominent 
F,  uneven  .* 
Very  britt$ 

& 

6 

Compact     massive  ; 
pointed  pyramids  with 
horizontally    striated 
faces 

Often  with  sphalerite, 
galena,  quartz;  sometimes 
with  gold;  whiter  than 
pyrite  or  marcasite;  more 
common  than  smaltite 

Isom. 

C,  not  important 
F,  granular 
Brittle 

6.5 

Com  pac  t  ;  massive  ; 
reticulated 

Often  with  copper-red 
niccolite,  erythrite 

Isom. 

C,  cubic,  not  prom- 
inent 
Brittle 

6.3 

Crystals  commonly; 
cubes;  pyritohedrons  ; 
massive 

Often  with  smaltite,  nic- 
colite; crystals  usually 
tarnished  to  pale  copper- 
red  color 

Orth. 

C,  not  prominent 
F,  uneve.n 
Brittle 

4.9 

Stalactitic  with 
rough  surfaces;  cox- 
comb; radiate;  col- 
umnar ;  low  pyra- 
mids; massive 

Never  in  cubes  or  pyrito- 
hedrons, and  different  in 
form  from  pyrite 

Isom. 

C,  not  important 
F,  uneven 
Brittle 

4.9 
5.4 

Compact;   massive 

Usually  tarnished  to  pea- 
cock colors;  occurs  with 
quartz,  chalcocite,  chalco- 
pyrite 

Orth. 

C,  prismatic      and 
prominent 
Brittle 

4.4 

Massive 

Often  with  chalcocite, 
bornite 

Hex. 

C,  perfect  and  prom- 
inent in  crystals 
Brittle 

5.3 
5.6 

Acicular;  capillary; 
hair  tufts;  compact 
fibrous  layers 

Always  needle-like  or 
fibrous;  often  in  cavities  in 
chert  or  red  hematite,  or 
coating  pyrrhotite 

Tetrag. 

C,  not  important 
F,  uneven   to   con- 
choidal 
Brittle 

4.2 

Massive  ;        tetrahe- 
dral  crystals 

Often  with  pyrite,  galena, 
sphalerite,  tetrahedrite, 
cnalcocite,  dolomite,  etc.  ; 
often  tarnished  peacock 
colors 

Hex. 

C,  not  important 
F,  uneven 
Brittle 

4.6 

Massive  ;  granular  ; 
occasional  crystals 

Usually  slightly  mag- 
netic; surface  often  tar- 
nished dark  bronze-brown 

m 

16 


STREAK  DARK  GRAY 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

BRASS,  BRONZE,  COP- 
PER-RED, OR  BROWN. 

NlCCOLITE 

NiAs 

Pale  cop- 
per-red 

Brownish 
black 

Metallic 

5 
5.5 

PYRITE 

FeS2 

Pale  brass- 
yellow 

Greenish 
black 
Brownish 
black 

Metallic 

6 
6.5 

MARCASITE 

FeS2 

Pale  brass- 
yellow 

Greenish 
black 
Brownish 
black 

Metallic 

6 
6.5 

STREAK  METALLIC  WHITE 


I 

2 

i 

§ 

w 

H 

2 
a 

! 

8 

MERCURY 

Hg 

Tin-white 

Metallic 

1 
1.5 

MOLYBDENITE 

MoS2 

Bluish 
lead-gray 

Lead-gray 
with  often 
greenish 
tinge 

Metallic 

SYLVANITE 
CALAVERITE 

(AuAg)Tea 

Silver-    or 
tin-  white  ; 
often  with 
brassy 
tinge 

Silver- 
white 

Metallic 

1.5 
2 

BISMUTH 

Bi 

Reddish 
white  to 
light  cop- 
per-red 

Silver- 
white 
Lead-gray 

Metallic 

2 

2.5 

2^5 

SILVER 

Ag 

Silver- 
white 

Silver- 
white 

Metallic 

ANTIMONY 

Sb 

Tin-white 
Silver- 
white 

Silver- 
white 

Metallic 

3 
3.5 

ARSENIC 

As 

Tin-white 
Light 
lead-    o  r 
steel-gray 

Tin-white 

Metallic 

3.5 

PLATINUM 
PLATINIRIDIUM 

Pt 
Ptlr 

Tin-white 
Light  steel- 
gray 

Light  steel- 
gray 

Metallic 

4 
4.5 

OR  IRON-BLACK. 


17 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  none 
F,  uneven 
Brittle 

7.5 

Compact;  impalpa- 
ble massive 

Usually  with  smaltite 

Isom. 

C,  indistinct 
F,  uneven 
Brittle 

5 

Cubes;  pyritohe- 
drons  ;  octahedrons  ; 
massive;  granular 

Very  common  ;  associ- 
ated with  all  sulphides- 
and  in  all  rocks 

Orth. 

C,  not  important 
F,  uneven 
Brittle 

4.9 

Coxcomb  and 
curved  dome  shapes; 
stalactitic  with 
rough  faces 

Distinguished  from  py- 
rite  by  form  generally 

TO  LIGHT  LEAD-  OR  STEEL-GRAY. 


13.6 

Liquid  globules 

Occurs  as  smpll  globules 
on  cinnabar 

Hex. 

C,  basal,  perfect  and 
prominent 
Sectile 

4.7 

Foliated  masses; 
scales;  flakes 

Soft  and  greasy,  like- 
graphite;  highly  flexible; 
often  with  quartz 

Mono. 

C,    clinopinacoidal, 
perfect,  promi- 
nent 
F,  coarse  granular 
Brittle 

9.9 
8.3 

Massive;  crystals 
with  deeply  striated 
faces 

Often  in  gray  phonolite 
rock  with  purple  fluorite; 
also  in  schist 

Hex. 

C,  basal,  perfect  and 
prominent 
Brittle 

9.7 

Reticulated;  em- 
bedded lenticular 
crystals;  massive 

Often  as  lenticular  crys- 
tals or  grains  in  quartz 

Isom. 

C,  none 
F,  hackly 
Malleable 

10.1 
11.1 

Wires;  arborescent; 
massive;  filiform 

Usually  tarnished  on  sur- 
face to  brown  or  black; 
often  with  barite,  calcite, 
other  silver  ores 

Hex. 

C,  basal,  prominent 
Brittle 

6.7 

Massive;  lamellar 

Often  with  stibnite;  usu- 
ally coated  with  whitish 
oxide  of  antimony 

Hex. 

C,  basal,  not  usually 
prominent 
F,  granular 
Brittle 

5.6 

Rounded  reniform 
masses;  granular 

Usually  tarnished  dull 
black  on  surface 

Isom. 

C,  none 
F,  hackly 
Malleable 

14 
19 

Nuggets;  grains 

In  gold-bearing  sands 

18 


STREAK  RED 


(  COLOR  RED  OR  BROWN.  | 

Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

1 
2 

BAUXITE 

Al203-f2H20 

Brown 

Reddish 
brown 

Earthy 
Dull 

HEMATITE 

Fe203 

Brownish 
red 
Cherry-red 

Dark  red 
Cherry-red 

Earthy 
Dull 

1 
4 

ERYTHRITE 

Co3As2O8+8H2O 

Peach-red 
Crimson 

Pale  red 

Earthy 
Vitreous 

1 
2.5 

1 

3 

WAD 

MnO,H2O 

Dark 
brown 

Dark  red- 
dish 
brown 

Earthy 
Dull 

CINNABAR 

HgS 

Scarlet  red 
Vermillion 
Dark  red 

Scarlet 
Vermillion 

Adaman- 
tine 

2 
2.5 

2 
2.5 

PROUSTITE 

Ag3AsS3 

Scarlet 
Vermillion 

Scarlet 

Adaman- 
tine 

COPPER 

Cu 

Copper-red 

Copper-red 

Metallic 

2.5 
3 

3.5 
4 

SPHALERITE 

ZnS 

Dark 
brown 

Reddish 
brown 

Resinous 
Vitreous 

CUPRITE 

Cu2O 

Dark  red 

Cochineal- 
red 
Brick-red 
Crimson- 
red 

Adaman- 
tine 
Earthy 

3.5 
4 

HEMATITE 

Fe203 

Dark 
brownish 
red 

Brownish 
red 

Submetallic 

4.5 

TURGITE 

2Fe2O3H2O 

Brown 

Reddish 
brown 

Submetallic 

5 

6 

OR  RED-BROWN. 


19 


System 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

C,  none 
F,  earthy 

2.5 

Claylike  masses  with 
small  rounded  concre- 
tions; pisolitic 

Clay  odor;  distinguished 
from  clay  by  pisolitic 
structure 

C,  none 
F,  earthy 

5 

Earthy  masses; 
oolitic;  powder 

Red  ochre  ;  often  red  clay 

Mono. 

C,  not  important 
F,  usually  earthy 

2.9 

Earthy;  crusts; 
rarely  in  crystals 

Occurs  with  cobalt  and 
nickel  ores  as  coatings 
and  crusts 

Amorph. 

C,  none 
F,  earthv 
Brittle 

4 

Earthy  masses; 
powder  concretions 

Often  with  psilomelane, 
limonite,  malachite,  azurite 

Hex. 

C,  prismatic,     not 
important 
F,  uneven 
Sectile 

8 
8.2 

Granular;  crystals; 
powder;  massive; 
compact 

Occurs  with  marcasite, 
chalcedony,  quartz,  sul- 
phur; very  heavy;  often 
mixed  with  siliceous  rock 
and  apparently  hard 

Hex. 

C,  rhombohed  r  a  1  , 
not  prominent 
Brittle 

5.6 

Crystals;  red  bands 
or  streaks  in  rock 

Light  ruby  silver  ore; 
often  with  gray  pyrargy- 
rite 

Isom. 

C,  none 
F,  hackly 
Malleable 

8.8 

Hackly  masses; 
sheets  ;  wires,  arbores- 
cent forms 

Usually  tarnished  black 
on  surface  ;  often  with  cal- 
cite,  cuprite,  malachite 

Isom. 

C,  dodecah  e  d  r  a  1, 
perfect  and 
prominent 
Brittle 

4 

Massive;  crystals 

Often  with  galena,  py- 
rite,  arsenopyrite,  etc. 

Isom. 

C,  poor 
F,  uneven 
Brittle 

5.9 

Massive  ;    com  pac  t  ; 
crystals;  octahedrons; 
cubes 

Usually  with  malachite, 
copper 

Hex. 

C,  none 
F,  uneven;     splin- 
tery 
Brittle 

5 

Massive  ;  renif  orm  , 
mamillary  ;  botryoid- 
al;  splintery;  oolitic 

Massive  red  hematite 

C,  none 
F,  splintery 
Brittle 

4.2 
4.4 

Compact  •  fibrous  ; 
massive;  botryoidal; 
earthy 

Resembles  limonite;  dis- 
tinguished by  streak; 
fibers  often  with  satin-like 
luster 

20 


STREAK  RED 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

I  •  COLOR  DARK  GRAY  OR  BLACK. 

PYRARGYRITE 

Ag3SbS3 

Dark  steel- 
gray 

Purple-red 
Cherry-red 

Metallic 

2.5 

TETRAHEDRITE 

CugSbsS, 

Dark  lead 
or  steel 
gray 

Cherry-red 
Dark  red 
brown 

Metallic 

3 
4.5 

2.5 
4 

HEMATITE 

(Fe203 

Dark  steel- 
gray 
Iron-black 

Brownish 
red 

Metallic 
Brilliant 

SPHALERITE 

ZnS 

Brownish 
black 

Dark 
brown 

Resinous 
Submetallic 

3.5 
4 

4~ 

MANGANITE 

Mn203+H2O 

| 

Iron-black 
Dark  steel- 
gray 

Dark  red- 
dish 
brown 

Metallic 

WOLFRAMITE 

(Fe,Mn)W04 

Dark  gray- 
ish or 
brownish 
black 

Dark  red- 
dish 
brown 

Submetallic 
Metallic 

5 
5.5 

5.5 

CHROMITE 

FeCr8O4 

Black 
Brownish 
black 

Grayish 
brown 

Submetallic 
to 
pitch-like 

PSILOMELANE 

MnO,H2O 

Dull  black 

Very  dark 
brown 

Submetallic 
Dull 

5 
6 

5.5 
6.5 

5.5 

6 

HEMATITE 

Fe203 

Iron-black 
Dark  steel- 
gray 

Cherry-red 
Brownish 
red 
Red-brown 

Metallic 

ILMENITE 

(Fe,Ti)203 

Iron-black 

Very  dark 
brown 

Metallic 

FRANKLINITE 

(Fe,Mn,Zn)304 

Iron-black 

Dark  red- 
dish 
brown 
Blackish 
brown 

Metallic 

5.5 
6.5 

OR  RED-BROWN. 


21 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  not  important 
F,  uneven 
Brittle 

5.8 

Massive  ;  granular  ; 
bands  and  streaks  in 
rock 

Usually  as  gray  bands 
mixed  with  red,  in  quartz 
rock;  dark  ruby  silver 
ore 

Isom. 

C,  none 
F,  uneven 
Brittle 

4.4 
5.1 

Massive  ;  tetrahe- 
dral  crystals 

Often  has  brilliant  luster 
with  brassy  tinge;  in 
quartz  with  sulphides 

Hex. 

C,  micaceous 
Brittle 

4.9 
5.3 

Foliated;  platy; 
micaceous 

Specular  hematite;  very 
bright  sparkling  plates  or 
scales 

Isom. 

C,  dodecahed  r  a  1  , 
prominent 
Brittle 

4 

Massive 

Often  with  galenite,  py- 
rite,  chalcopyrite,  tetra- 
hedrite 

Orth. 

C,  brachypinacoid- 
al,  prominent 
Brittle 

4.4 

Prisms;  columnar; 
acicular 

• 

Prisms  often  in  bunches 
with  prism  faces  deeply 
striated  vertically;  occurs 
with  pyrolusite 

Mono. 

C,   clinopinacoidal, 
perfect   and 
prominent 
Brittle 

7.5 

Thick  tabular  crys- 
tals; massive;  com- 
pact 

Often  with  cassiterite, 
quartz,  fluorite 

Isom. 

C,  none 
F,  uneven 
Brittle 

4.3 
4.6 

Massive  ;    granular 

Sometimes  coated  with 
green,  garnet;  often  with 
serpentine 

C,  none 
F,  conchoidal 
Tough  to  brittle 

3.7 
4.7 

Impalpable  ;  mas- 
sive; stalactitic;  bo- 
tryoidal,  round 
masses 

Often  with  powdery 
pyrolusite 

Hex. 

C,  none 
F,  uneven 
Brittle 

4.9 
5.3 

Massive  ;  gram  il  ar  ; 
foliated  ;  crystals  ; 
scales;  micaceous 

Crystals  often  have  an 
iridescent  tarnish  ;  fine 
scaly  specular  variety 
seems  soft 

Hex. 

C,  none 
F,  conchoidal 
Brittle 

4.5 
5 

Rounded  pebbles  ; 
sand  ;  plates  ;  mas- 
sive 

Sometimes  slightly  mag- 
netic 

Isom. 

C,  none 
F,  uneven 
Very  brittle 

5 
5.2 

Rounded     crystals  ; 
Octahedrons;    granu- 
lar masses 

Usually      with      zincite, 
willemite,     calcite  ;     mag- 
netic but  not  so  stronrly- 
as  magnetite 

22 


STREAK  RED 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 
6 

BLACK. 

COLUMBITE 

(Fe,Mn)(Nb,Ta)2O6 

Pitch- 
black 

Dark 
brown 

Submetallic 
Vitreous 

CASSITERITE 

SnO2 

Black 

Dark 
brown 

Submetallic 
to 
Metallic 

6 
7 

STREAK  YELLOW 


REALGAR 

AsS 

Bright  red 
Orange- 

Orange 
yellow 

Adaman- 
tine 

1.5 
2 

red 

Resinous 

Vitreous 

g 

ZINCITE 

ZnO 

Dark  red 

Orange- 

Vitreous 

4 

s 

Blood-red 

yellow 

4.5 

8 

« 

ORPIMENT 

AS-jSg 

Lemon- 

Lemon- 

Adaman- 

1.5 

yellow 

yellow 

tine 

2 

Resinous 

Pearly 

REALGAR 

AsS 

Orange- 
yellow 

Orange- 
yellow 

Resinous 
Vitreous 

1.5 
2 

SULPHUR 

S 

Sulphur- 
yellow 
Honey- 

Pale  yel- 
low 

Resinous 
Greasy 
Vitreous 

1.5 
2.5 

yellow 

Straw- 

tf 

o 

yellow 

8 

LIMONITE 

2Fe2O3.3H2O 

Yellow 

Yellow 
Brown 

Earthy 
Dull 

2 
4 

GOLD 

Au 

Golden 

Golden 

Metallic 

2.5 

yellow 

yellow 

3 

SPHALERITE 

ZnS 

Brownish 
yellow 

Pale  yel- 
low 

Resinous 

3.5 
4 

OR  RED-BROWN. 


23 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  not  important 
F,  uneven 
Brittle 

5.3 
7.3 

Crystals,  usually  in 
parallel  groups 

Occurs  in  granite,  often 
with  albite,  tourmaline, 
beryl 

Tetrag. 

C,  imperfect 
F,  uneven 
Brittle 

6.8 
7.1 

Massive 

Often  in  quartz  -  mica 
rock  with  wolframite, 
fluorite 

OR  YELLOW-BROWN. 


Mono. 

C,    clinopinacoidal, 
not  prominent 
F,  conchoidal 
Sectile 

3.5 

Massive  ;  granular  ; 
crystals 

Often  with  orpiment; 
disseminated  in  siliceous 
rock  and  often  apparently 
hard 

Hex. 

C,    basal,     perfect 
and  prominent 
F,  uneven 
Brittle 

5.4 
5.7 

Massive  ;  lamellar  ; 
granular 

Occurs  with  franklinite, 
willemite,  calcite 

Orth. 

C,  brachypinacoid- 
al,  perfect  and 
prominent 
Sectile;  flexible 

3.5 

Foliated  ;     plates 
massive 

Usually  with  realgar 

Mono. 

C,    clinopinacoidal, 
not  prominent 
F,  conchoidal 
Brittle;  sectiie 

3.5 

Crystals  ;  massive  ; 
granular 

Often  with  orpiment  or 
finely  mixed  quartz 

Orth. 

0  '  * 

C,  indistinct 
F,  conchoidal 
Brittle 

2 

Crystals;  pyramids; 
crusts 

Often  with  celestite,  ara- 
gonite,  limestone,  cinna- 
bar, gypsum 

C,  none 
F,  earthy 

3.6 

Earthy  m  a  s  s  e  s  5 
ochre  powder 

Yellow  ochre;  often  yel- 
low clay 

Isom. 

C,  none 
F,  hackly 
Highly  malleable 

15.6 
19.3 

Scales;  flakes; 
leaves;  grains  ;  wires  ; 
nuggets 

Usually  in  quartz,  con- 
glomerates, or  schists; 
sometimes  with  pyrite  or 
arsenopyrite 

Isom. 

C,  dodecah  e  d  r  a  1  ; 
prominent 
F,  uneven 
Brittle 

4 

Massive  ;  cleavage 
masses;  crystals 

Usually  with  galena,  py- 
rite, chalcopynte,  tetKV- 
hedrite,  quartz,  calciteT 
dolomite 

24 


STREAK  YELLOW 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

YEL'OW 

PYROMORPHITE 

(PbCl)Pb,P3012 

Greenish 
yellow 
Wax-yel- 
low 

Greenish 
yellow 

Adaman- 
tine 

3.5 

4 

BAUXITE 

A1203.2H20 

Brown 

Brownish 
yellow 

Earthy 
Dull 

1 
3 

LIMONITE 

2Fe2O3.3H8O 

Brown 

Brownish 
yellow 
Yellowish 
brown 

Earthy 
Dull 

2 
4 

SPHALERITE 

ZnS 

Brown 
Brownish 
black 

Brownish 
yellow 

Resinous 

3.5 
4 

DR  BLACK. 

SIDERITE 

FeCOg 

Pale 
brown 
Grayish 
brown 
Dark 
brown 

Pale  yel- 
low 
Yellowish 
brown 

Vitreous 

3.5 
4 

1 

GOETHITE 

Fe2O3.H2O 

Yellowish 
brown 

Yellowish 
brown 
Brownish 
yellow 

Submetallic 

5 
5.5 

COLOR 

LIMONITE 

2Fe203-3H20 

Yellowish 
brown 
Dark 
brown 

Brownish 
yellow 
Yellow- 
brown 

Submetallic 

5 
5.5 

- 

CHROMITE 

FeO2O4 

Black 

Grayish 
brown 

Submetallic 
Pitchlike 

5.5 

BROOKITE 

TiO2 

Dark 
brownish 
black 

Pale  yel- 
low 
Grayish 
brown 

Submetallic 
Metallic 

5.5 

6 

RUTILE 
t 

TiO2 

Reddish 
brown 
Black 

Pale  yel- 
lowish 
brown 

Adaman- 
tine 
Metallic 

6 
6.5 

OR  YELLOW-BROWN. 


25 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  not  prominent 
F,  uneven 
Brittle 

6.5 
7.1 

Small  hexagonal 
prisms;  massive 

Often  with  galena,  cerus- 
site,  anglesite,  mimetite 

C,  none 
F,  earthy 

2.5 

Clay-like  masses; 
pisolitic 

Clay  odor;    distinguished 
from    kaolin  ite    (clay)    by 
pisolitic  structure 

C,  none 
F,  earthy 

3.6 

Massive;  earthy 

Brown    ochre    or   brown 
clay  (kaolinite) 

Isom. 

C,  dodecahedral, 
prominent 
F,  uneven 
Brittle 

4 

Massive;  .  cleavage 
masses;  crystals 

Common  color;  occurs 
with  galena  in  chert;  also 
with  many  sulphides 

Hex. 

C,  rhomboh  e  d  r  a  1, 
perfect  and 
prominent 
Brittle 

3.8 

Rhombohedrons; 
cleavage  masses; 
crystals  with  curved 
faces 

Often  with  cryolite, 
quartz,  hematite,  fluorite 

• 

Orth. 

C,  brachypinacoid- 
al,  prominent 
F,  uneven 
Brittle 

4 
4.4 

Acicular  ;  stalactitic  ; 
radiate;  fibrous 

Of  ten  in  cavities  in  limon- 
ite  or  hematite;  distin- 
guished from  limonite  by 
crystals  and  cleavage 

C,  none 
F,  uneven 
Brittle 

3.6 
4 

Compact;    massive; 
stalactitic  ;    botryoid- 
al;  columnar 

Often  in  cubes  as  an 
alteration  from  pyrite; 
very  common  iron  oxide; 
botryoidal  masses  often 
have  black  varnish-like 
surfaces 

Isom. 

C,  none 
F,  uneven 
Brittle 

4.3 
4.5 

Massive 

Often  coated  with  green 
garnets;  often  with  ser- 
pentine 

Orth. 

C,  not  important 
F,  uneven 
Brittle 

3.8 

4 

Square      pyramids  ; 
hexagonal  shaped 
pyramids 

Always  in  'crystals;  faces 
deeply  striated;  not 
twinned  like  rutile 

1 

Tetrag. 

C,  not  important 
F,  uneven 
Brittle 

4.2 

Twinned    crystals  ; 
long  acicular  crystals 

Faces  deeply  striated  ; 
knee-shaped  twins;  often 
in  quartz 

26 


STREAK  YHLLOW 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

4 
m 

« 
o 

i 

CASSITERITE 

SnO2 

Black 
Reddish 
brown 
Yellowish 
brown 
Pale  yellow 

Pale  yel- 
low 
Pale  gray- 
ish brown 

Submetallic 

6 

7 

I  COLOR  GREEN. 

PYROMORPHITE 

(Pb,Cl)Pb4(P04)3 

Yellowish 

Grass- 
green 

Pale  green- 
ish yellow 

Adaman- 
tine 
Vitreous 

3.5 
4 

EPIDOTE 

HCa2(Al,Fe)2Si3013 

Yellowish 
green 
Deep 
green 
Oil-green 

Pale  yel- 
low 

Vitreous 

6 

7 

STREAK  BLUE 


j  COLOR  BLUE,  GREEN,  OR  BLACK. 

ANNABERGITE 

Ni3As2O8+8H2O 

Apple- 
green 

Pale  green 

Vitreous 
Earthy 

1 

VIVIANITE 

Fe3P2O8+8H2O 

Dark  blue- 
green 
Indigo- 
blue 

Indigo- 
blue 

Vitreous 
Earthy 

1.5 
2 

CHLORITE 

PROCHLORITE 
CLINOCHLORE 

Mg3FeAl2Si2011 
+  4H20 

Dark 
green 

Grayish 
green 

Vitreous 
Pearly 

1.5 
2.5 

LlNARITE 

CuPbSO5.H2O 

Deep 
azure- 
blue 

Smalt-blue 
Pale  blue 

-Adaman- 
tine 
Vitreous 

2.5 

2 
4 

CHRYSOCOLLA 

CuSiO3+2H2O 

Bluish 
green 
Greenish 
blue 

Pale  green 
Pale  blue 

Vitreous 
Greasy 
Earthy 

AZURITE 

2CuCO3.Cu(OH)2 

u^V^ 

Azure-blue 

Smalt-blue 

Vitreous 
Velvety 

3.5 
4 

MALACHITE 

CuCO3.Cu(OH)2 

Bright 
green 
Emerald- 
green 
Dark 
green 

Emerald- 
green 

Vitreous 
Silky 
Velvety 
Dull    ' 

3.5 
4 

OR  YELLOW-BROWN. 


27 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Tetrag. 

C,  not  important 
F,  uneven 
Brittle 

6.8 
7.1 

Pebbles  with  con- 
centric structure; 
crystals;  massive 

Stream  tin;  wood  tin 

Hex. 

C,  not  important 
F,  uneven 
Brittle 

6.5 
7.1 

Small  hexagonal 
prisms;  drusy  crusts; 
massive 

Very  heavy  ;  usually  with 
ores  of  lead 

Mono. 

C,  basal,    perfect 
and    usually 
prominent 

3.2 
3.5 

Prismatic;  colum- 
nar; reticulated 
masses 

Often    in    quartz    and 
schists;  also  with  calcite 

OR  GREEN. 


Mono. 

C,  none 
F,  earthy 

Fine  capillary  coat- 
ings 

Occurs  with  erythrite  as 
coatings  and  crusts  on 
cobalt  and  nickel  ores 

Mono. 

C,  c  1  inopinacoidal, 
perfect      in 
crystals 
Brittle 

2.6 

Slender  prismatic  ; 
acicular;  earthy 

Often  as  crystals  in  pyr- 
rhotite;  as  earthy  round 
masses  in  clay 

Mono. 

C,  basal,  perfect 
and  prominent 
Tough  to  brittle 

2.8 

Micaceous  scaly 
flakes;  compact 
scaly  masses 

Highly  flexible  but  not 
elastic,  like  mica  ;  often  al- 
tered from  biotite 

Mono. 

C,  orthopinacoidal, 
usually  promi- 
nent 
Brittle 

5.4 

Columnar  ;  fibrous  ; 
long  prisms  some- 
times radiate 

Usually  with  galenite: 
heavier  than  azurite,  and 
shows  cleavage  faces 

Amorph. 

C,  none 
F,  uneven 
Brittle 

2 
2.3 

Massive;  stains; 
earthy  - 

Usually  with  copper  ores; 
darker  and  glassier  bluish 
green  than  malachite,  and 
never  fibrous 

Mono. 

C,  not  prominent 
Brittle 

3.8 

Crystals;  fibrous; 
acicular 

Usually  with  malachite 
and  often  with  limonite, 
wad 

Mono. 

C,  not  prominent 
F,  uneven;  splin- 
tery 
Brittle 

4 

Fibrous;  banded; 
stalactitic;  botryoid- 
al;  powder 

Often  with  cuprite,  cop- 
per, chalcocite,  chalcopy- 
rite;  often  as  green  stains 
in  ore  rocks 

28 


STREAK  BLUE 


Name. 

Composition. 

Color. 

Streak. 

Luster. 

H. 

COLOR  BLUE,  GREEN,  OR  BLACK. 

ALABANDITE 

MnS 

Black 

Dark  gray- 
ish green 

Submetallic 

3.5 
4 

LAZURITE 
LAPIS  LAZULI 

NaAlSi04 

Azure-blue 
Ultrama- 
rine blue 

Pale  blue 

Vitreous 
Greasy 

5 
5.5 

~6~ 

6 

AUGITE 

MgCa2FeSi4O12 

Greenish 
black 
Blackish 
green 

Pale 
grayish 
green 

Vitreous 

HORNBLENDE 

Mg3Ca2FeSiflO18 

Greenish 
black 
Blackish 
green 

Pale 
grayish 
green 

Vitreous 

Silky 

5 

6 

GLAUCOPHANE 

Silicate  of  Na,Al. 
Mg,Fe 

Lavender- 
blue 
Blackish 
blue 

Grayish 
blue 

Vitreous 
Pearly 

6 
6.5 

STREAK  UNCOLORED,  WHITE, 


COLOR  YELLOW  OR  BROWN. 

Name. 

Composition. 

Color. 

Luster. 

H. 

CERARGYRITE 

AgCl 

Dark  gray 
Dark  brown 

Waxy 
Adaman- 
tine 

1 
1.5 

BAUXITE 

A12O3+3H2O 

Yellow  to  brown 

Earthy 
Dull 

1.5 
3 

KAOLINITE 

(Clay) 

H4Al2Si2O9 

Yellow  to  brown 

Earthy 
Dull 

1.5 
2.5 

GYPSUM 

CaSO4+2H2O 

Yellow  to  brown 

Vi  treous 
Silky 
Dull 

1.5 
2 

SULPHUR 

S 

Sulphur-yellow 
Honey-yellow 
Brown 

Vitreous 
Greasy 

1.5 
2 

OR  GREEN. 


29 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Isom. 

C,  not  prominent 
F,  uneven 
Brittle 

4 

Massive 

Often  with  rhodochro- 
site,  pyrite,  argentite,  ga- 
lena; surface  usually  tar- 
nished brown 

Isoin. 

C,  not  important 
Brittle 

2.4 

Massive  ;      dissemi- 
nated in  rock 

Often    with    calcite    and 
pyrite 

Mono. 

C,    prismatic,     not 
usually    promi- 
nent 
Cleavage  angle  87° 
Brittle 

3.2 
3.6 

Almost       square 
prisms  ;   massive 

Distinguished  from  horn- 
blende by  cleavage  angle; 
also  more  often  in  crystals 

Mono. 

C,    prismatic     and 
very  prominent 
Cleavage  angle  124° 
Brittle 

2.9 
3.4 

Massive;  crystals 
rare 

Usually  with  bright  cleav- 
age faces  having  a  fibrous 
appearance 

Mono. 

C,    prismatic,    per- 
fect 
Brittle 

3.1 

Fibrous;   columnar; 
reticulated 

Usually  forms  schists; 
a  blue  hornblende 

OR  LIGHT  GRAY. 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Isom. 

C,  none 
Very  sectile 

5.5 

Thin  crusts;  coat- 
ings; massive 

Cuts  like  wax;  often  with 
silver  ores 

C,  none 
F,  earthy 

2.5 

Compact  earthy; 
pisolitic 

Clay  odor;  distinguished 
from  kaolinite  (clay)  by 
pea-shaped  structure 

Mono. 

C,  none 
F,  earthy 

2.6 

Compact  earthy; 
soapy;  friable 

Clay  odor;  massive  clay; 
occasionally  soapy  feel 

Mono. 

C,  pinacoidal,  per- 
fect and  promi- 
nent 
Brittle 

2.3 

Fibrous;  columnar; 
granular;  compact 
massive 

Ferruginous  gypsum 

Orth. 

C,  not  important 
F,  uneven 
Brittle 

2 

Crystals;  pyramids; 
crusts. 

Often  with  limestone, 
celestite,  aragonite,  cinna- 
bar 

30 


STREAK  UNCOLORED,  WHITE, 


COLOR  YELLOW  OR  BROWN.  | 

Name. 

Composition. 

Color. 

Luster. 

H. 

CHLORITE 

PROCHLORITE 
CLINOCHLORE 
PENNINITE,  etc. 

Ha(Mg,Fe)*AL£iaOi8 

Dark  yellowish 
brown 
Greenish  brown 

Vitreous 
Pearly 

1.5 
2.5 

BIOTITE 

(HK)?(Mg,Fe)2(Al,Fe)2- 
(SiO4)3 

Dark  brown 
Greenish  brown 

Pearly  to 
Vitreous 

2.5 
3 

PHLOGOPITE 

HJKMgaAHSiOO, 

Light  brown 
Cinnamon-brown 

Pearly 
Vitreous 

2.5 
3 

HALITE 

NaCl 

Light  yellow  or 
brown 

Vitreous 

2.5 

CRYOLITE 

Na^Fe 

Grayish  brown 

Vitreous 
Icy 

2.5 
3 

CALCITE 

CaCO3 

Honey-yellow 
Light  to  dark 
brown 

Vitreous 

3 

BARITE 

BaSO4 

Lemon-yellow 
Yellowish  brown 

Vitreous 

2.5 
3.5 

SERPENTINE 

(H3(MgOH)Mg2(Si04)2 

Greenish  brown 
Yellowish  brown 

Greasy 
Vitreous 

2.5 
4 

CERUSSITE 

PbCO3 

Grayish  brown 
Yellowish  brown 

Adaman- 
tine 
Earthy 

3 
3.5 

WULFENITE 

PbMoO4 

Lemon-yellow 
Orange-yellow 

Greasy 
Adaman- 
tine 

3 

MlMETITE 

(PbCl)Pb4(As04)3 

Brownish  yellow 
Yellow-brown 

Adaman- 
tine 
Greasy 

3.5 

PYROMORPHITE 

(PbCl)Pb4(P04)3 

Greenish  yellow 
Yellowish  brown 

Greasy 
Adaman- 
tine 

3.5 
4 

OR  LIGHT  GRAY. 


31 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Mono. 

C,  basal,  perfect  and 
prominent 
Tough 

2.9 

Micaceous;  scales; 
flakes  ;  compact 
scaly  masses 

Highly  flexible  but  not 
elastic,  like  the  micas; 
often  an  altered  biotite 

Mono. 

C,  basal,  perfect  and 
very  prominent 
Tough 

2.7 
3.1 

Mica  plates;  scales; 
flakes 

Dark  color  even  in  thin- 
nest plates  ;  flexible  and 
elastic;  black  mica 

Mono. 

C,  basal,  perfect  and 
prominent 
Tough 

2.8 

Micaceous;  scales; 
flakes;  sheets 

Lighter  brown  than  bio- 
tite ;  almost  colorless  in 
thin  sections;  brown  mica 

Isom. 

C,  cubic,  perfect  and 
prominent 
Brittle 

2.1 
2.6 

Cubes;  massive; 
granular 

Tastes  salt 

Mono. 

C,  basal,  prominent, 
and   pinacoidal 
not  so  good 

3 

Massive 

Three  cleavages  almost 
at  right  angles,  making 
cubes;  usually  with  sider- 
ite 

Hex. 

G,   r  h  o  mbohedral, 
very  prominent 
Brittle 

2.7 

Rhomboh  e  d  r  o  n  s  ; 
scalenohedrons;  gran- 
ular; massive 

Rhombohedral  cleavage 
very  characteristic  ;  very 
common  mineral 

Orth. 

C,  basal   and    pris- 
matic,    perfect 
and  prominent 

4.3 
4.6 

Massive  ;  platy  crys- 
tals 

Heavy,  vitreous  mineral; 
often  with  galena 

Mono. 

C,  not  important 
Brittle 

2.6 

Massive;  compact. 

Very  smooth  feel,  almost 
greasy 

Orth. 

C,  not  prominent 
F,  conchoidal 
Very  brittle 

6.5 

Massive;  crusts 

Usually  with  galenite  or 
anglesite;  very  heavy 

Tetrag. 

C,  not  prominent 
Brittle 

6.7 

7 

Square  plates;  thin 
plates  ana  tables 

Often  with  vanadinite  or 
galenite 

Hex. 

C,  not  prominent 
Brittle 

7 
7.2 

Rounded  aggregates 
of  plates;  small  crys- 
tals 

Often  with  pyromor- 
phite,  galena 

Hex. 

C,  none 
Brittle 

6.5 
7.1 

Short  hexagonal 
prisms  ;  columnar 
masses 

Often  with  galena,  cerus- 
site,  anglesite  ;  crystal 
faces  deeply  striated  ver- 
tically 

32 


STREAK  UNCOLORED,  WHITE, 


COLOR  YELLOW  OR  BROWN. 

Name. 

Composition. 

Color. 

Luster. 

H. 

ARAGONITE 

CaCO3 

Honey-yellow 
Yellow-brown 

Vitreous 
Glassy 

3.5 
4 

STILBITE 

(Na2Ca)Al2Si6O10.6H2O 

Yellowish  brown 
Light  brown 

Vitreous 
Silky 

3.5 
4 

DOLOMITE 

(CaMg)CO3 

Yellowish  brown 
Grayish  brown 

Vitreous 

3.5 
4 

SIDERITE 

FeCO, 

Grayish  brown 
Dark  brown 

Vitreous 
Pearly 

3.5 
4 

SPHALERITE 

ZnS 

Honey-yellow 
Yellowish  brown 
Reddish  brown 

Resinous 

3.5 
4 

MAGNESITE 

MgC03 

Grayish  brown 

Vitreous 
Dull 

3.5 
4.5 

FLUORITE 

CaF2 

Lemon-yellow 
Pale  yellow 
Yellowish  brown 

Vitreous 
Glassy 

4 

SCHEELITE 

CaW04 

Yellowish  brown 
Grayish  brown 

Greasy 
Adaman- 
tine 

4.5 
5 

CALAMINE 

Wio, 

Pale  brown 

Vitreous 

4.5 
5 

SMITHSONITE 

ZnCO3 

Yellowish  brown 

Vitreous 

5 

APATITE 

(CaF)Ca4(PO«). 

Brown 
Greenish  brown 

Vitreous 
Greasy 

5 

OR  LIGHT  GRAY. 


33 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  not  prominent 
Brittle 

2.9 

Stalactitic;  banded; 
massive 

Differs  from  calcite  in 
not  having  prominent 
cleavage 

Mono. 

C,  clinopinacoidal 
Brittle 

2 
2.2 

Columnar;  sheaf- 
like  ;  fibrous 

Often  in  cavities  in  lava 
rocks,  with  chabazite,  heu- 
landite,  analcite 

Hex. 

C,  rhombohe  d  ra  1  , 
not  prominent 

2.9 

Massive 

Harder  than  calcite 

Hex. 

C,  rhomboh  e  d  r  a  1  , 
perfect  and  very 
prominent 

3.8 

Rhomb  ohedrons 
with  curved  faces; 
s  a  d  d  1  e-shaped  crys- 
tals; massive 

Often  in  cryolite;  more 
glassy  than  sphalerite 

Isom. 

C,  dodeca  h  e  d  r  a  1  , 
very  prominent 

3.9 
4.1 

Massive 

Resinous  cleavage  faces 
characteristic  ;  often  with 
galena,  tetrahedrite,  etc. 

Hex. 

C,  rhombohe  dral, 
prominent      i  n 
crystals 
F,  conchoidal 

3.1 

Massive;  rhombohe- 
drons 

Crystals  usually  in  talc; 
compact  impalpable  mass- 
es more  common 

Isom. 

C,  octahedral,   per- 
fect and  promi- 
nent' 
Very  brittle 

3.1 

Cubes;,  granular, 
massive 

Often  with  pyrite,  galena, 
and  sulphides 

Tetrag. 

C,  not  prominent 
Brittle 

5.9 
6.1 

Crystals;  pyramids; 
massive 

Often  with  wolframite, 
cassiterite;  very  heavy 

Orth. 

C,  prismatic,  prom- 
inent 

3.5 

Drusy  coatings; 
small  crystals 

Often  with  smithsonite 
on  yellow  earthy  masses 

Hex. 

C,  rhombohe  dral, 
not  prominent 

4.3 

4.5 

Small  rhombohe- 
dral  crystals;  drusy 
c  ry  stals  ;  bone-1  i  k  e 
masses 

Dry  bone;  often  with 
the  silicate  calamine;  also 
with  sphalerite 

Hex. 

C,  basal,  imperfect, 
not  prominent 
Brittle 

3.2 

Hexagonal  prisms; 
granular 

Green  and  brown  colors 
often  intermixed;  crystals 
often  have  fused  appear- 
ance 

34 


STREAK  UNCOLORED,  WHITE, 


COLOR  YELLOW  OR  BROWN.  | 

Name. 

Composition. 

i 

Color. 

Luster. 

H. 

MONAZITE 

(Ce,La,Di,Th)PO4 

Honey-yellow 
Brown 

Adaman- 
tine 
Vitreous 

5 
5.5 

TITANITE 

CaTiSiO8 

Dark  brown 
Brownish  yellow 

Adaman- 
tine 
Greasy 
Vitreous 

5 
5.5 

WlLLEMITE 

TROOSTITE 

ZngSiC^ 

Greenish  yellow 
.Reddish  brown 

Vitreous 

5.5 

OPAL 

SiO2+nH2O 

Yellow 
Brown 

Waxy 
Vitreous 

5.5 
6.5 

PYROXENE 

ENSTATITE 

MgSiO8 

Grayish  brown 
Greenish  brown 

Vitreous 
Pearly 

5.5 

BRONZITE 

(Mg,Fe)Si03 

Bronze-brown 

Vitreous 
Bronzy 

5 
6 

HYPERSTHENE 

(Fe,Mg)Si03 

Dark  brown 
Blackish  brown 

Bronze- 
metallic 
Vitreous 
Pearly 

5 

6 

AUGITE 

Silicate  of  Ca,  Mg,  Al,  and 
Fe,  chiefly 

Dark  brown 

Vitreous 

5 

6 

AMPHIBOLE 

ANTHOPHYL- 

LITE 

(Mg,Fe)Si03 

Light  grayish 
brown 
Brownish  gray 
Greenish  gray 

Vitreous 
Pearly 

5.5 
6 

TREMOLITE 

CaMg3(SiOs)4 

Grayish  brown 

Vitreous 
Silky 

5 
6 

HORNBLENDE 

Ca(MgFe)3(SiO3)4  with 
(MgFe)2(AlFe)4Si2012 
and  Na2Al2(SiO3)4 

Dark  reddish 
brown 

Vitreous 

5 
6 

OR  LIGHT  GRAY. 


35 


System. 

Cleavage  or  Fracture. 

G.           Common  Structure. 

Observations. 

Mono. 

C,  basal,  not  prom- 
inent 
Brittle 

5 
5.5 

Yellow  sand;  brown 
crystals 

Commonly  as  yellow 
sand;  crystals  rare 

Mono. 

C,  indistinct      usu- 
ally 
Brittle 

3.5 

Flat    wedge-shaped 
crystals;    massive 

Often  in  syenitic  rocks; 
often  with  hornblende  and 
magnetite  ;  masses  show 
cleavage 

Hex. 

C,  basal,  sometimes 
prominent 

3.9 
4.1 

Crystals;    granular; 
massive 

Often  in  calcite  with 
zincite,  franklinite 

Amorph. 

C,  none 
F,  conchoidal     and 
prominent 

2.2 

Massive;    wood-like 

Softer  than  brown  jas- 
per; wood  opal  shows 
wood  structure 

Orth. 

C,  prismatic       and 
brachypinaco  i  - 
dal,  very  prom- 
inent 
Brittle 

3.2 

Bladed,    columnar; 
massive 

Often  softer  because  of 
alteration  to  serpentine  ; 
pearly  cleavage  faces  usual 

Orth. 

C,  prismatic       and 
brachypinacoi- 
dal,  very  prom- 
inent 
Brittle 

3.5 

Reticulated  masses; 
columnar 

Bronze  luster  and  color 
characteristic 

Orth. 

C,  clinopinacoidal, 
very  prominent 
Brittle 

3.5 

Broad    cleavage; 
masses 

More  bronze  brown  than 
hornblende 

Mono. 

C,  prismatic,     not 
usually    promi- 
nent 
Cleavage  angle  87° 

3.5 

Crystals 

Distinguished  from  horn- 
blende by  the  prism  being 
nearly  square 

Orth. 

C,  prismatic    and 
prominent 

3.2 

Lamellar;     fibrous; 
reticulated;  columnar 

Often  soft  because  of 
alteration  ;  structure  re- 
sembles actinolite 

Mono. 

C,  prismatic       and 
prominent 

2.9 
3.4 

Bladed  ;    columnar  ; 
prismatic;    fibrous 

Cleavage  angle  124°; 
often  in  marble  or  calcite 
with  brown  tourmaline 

Mono. 

C,  prismatic,    very 
prominent 

3.4 

Crystals 

Prismatic  cleavage  angle 
about  124° 

36 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

NEPHELITE 
(Elseolite) 

NaAlSiO4 

Reddish  brown 

Greasy 
Vitreous 

5.5 

6 

ALLANITE 

(CaFe2)  (Al,Fe,Ce),(AlOH)- 
(Si04)3 

Dark  brown 
Blackish  brown 

Pitchy 
Subme- 
tallic 

5.5 
6 

SlLLIMANITE 

(Fibrolite) 

Al2SiO5 

Light  grayish 
brown 
Hair-brown 

Vitreous 

6 
7 

ZOISITE 

Ca2Al2(AlOH)(SiO4), 

Grayish  brown 
Yellowish  brown 

Vitreous 

6 
6.5 

EPIDOTB 

HCa2(Al,Fe)3Si3013 

Oil  brown 
Greenish  brown 
Greenish  yellow 

Vitreous 

6 

7 

RUTILE 

TiO2 

Reddish  brown 

Adaman- 
tine 

6 
6.5 

CASSITERITE 

SnO2 

Reddish  brown 
Yellowish  brown 

Adaman- 
tine 
Dull 

6 
7 

CHONDRODITE 

Mg3[Mg(F,OH)2(Si04)2] 

Reddish  brown 
Brownish  yellow 

Vitreous      6 
6.5 

AXINITE 

AlCa3(A10H)(B03)Si4012 

Clove-brown 
Yellow 

Vitreous      6.5 

:  7 

ORTHOCLASE 

KAlSi308 

Pale  brown 
Flesh-brown 

Vitreous 
Pearly 

6 
6.5 

QUARTZ 

var.  Citron 
Smoky 
Ferruginous 

SiO2 

Brownish  yellow 
Hair  brown 
Smoky  brown 
Yellowish  brown 
Reddish  brown 

Vitreous 

Glassy 
Greasy- 

7 

CHALCEDONY 

var.  Agate 
Jasper 
Flint 

;siO2 

Brown  or  yellow 
in  all  shades 

Waxy 
Vitreous 

7 

OR  LIGHT  GRAY. 


37 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  prismatic,      not 
prominent 
Brittle 

2.6 

Massive 

Usually     in     crystalline 
rock  with  feldspar,  biotite, 
leucite 

Mono. 

C,  not  important 
F,  uneven 
Brittle 

3.5 
4.2 

Thin  tabular  crys- 
tals; seldom  massive 

In  granitic  rocks  as  thin 
brownish,  pitch-like  crys-  " 
tals  and  streaks 

Orth. 

C,  brachypinacoid- 
al,     prominent 
Brittle 

3.2 

Long  slender  prisms; 
fibers;  columns 

Always  in  schist  rocks; 
fibers  often  bent  and  retic- 
ulated 

Orth. 

C,  brachypinacoid- 
al,     prominent 
Brittle 

3.2 

Stout  columns  ; 
sometimes  fibrous 
masses 

Columnar  crystals  usual- 
ly much  broken  by  cross- 
fracture 

Mono. 

C,   basal,     perfect, 
sometimes 
prominent 
Brittle 

3.2 
3.5 

Prismatic  crystals  ; 
columnar  ;  fine  gran- 
ular 

Often  as  prisms  in  quartz 

Tetrag. 

C,  prismatic,     not 
important 
Brittle 

4.2 

Twinned  crystals  ; 
long  prisms;  acicular 

Crystals     usually     with 
deeply   striated   faces; 
knee-shaped  twins 

Tetrag. 

C,  not  important 
F,  uneven 
Brittle 

6.8 

7 

Crystals;  rounded 
pebbles 

Pebbles  of  reddish,  gray- 
ish,  and  yellowish  color, 
with      often      concentric 
structure 

Mono. 

C,  not  prominent 
F,  uneven,  brittle 

3.2 

Crystals;  embedded 
grains  in  rock 

Often    in    calcite     with 
octahedrons  of  spinel 

Trie. 

C,  not  prominent 
F,  conchoidal 
Brittle 

3.2 

Thin  sharp-edged 
crystals 

Often  with  garnet,  tour- 
maline, albite,  quartz 

Mono. 

C,  basal  and  clino- 
pinacoidal,  very 
prominent 

2.6 

Crystals  ;  cleavage 
pieces  ;  massive 

Commonly  with   quartz, 
mica,      hornblende  ;      two 
cleavages  at  R.  A. 

Hex. 

C,  none 
F,  conchoidal 
Very  prominent 
Brittle 

2.6 

Hexagonal  prisms 
and  pyramids  ;  prism 
faces  usually  horizon- 
tally striated;  mas- 
sive. 

Smoky  quartz  common  in 
granites  with    orthoclase, 
biotite,  or  hornblende  ;  con- 
choidal fracture  character- 
istic 

Hex. 

C,  none 
F,,  conchoidal 
Very  prominent 
Brittle 

2.6 

Colloidal  masses; 
often  banded;  botry- 
oidal;  mammillary 

Conchoidal  fracture,  very 
characteristic 

38 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

COLOR  BELLOW  OR  BROWN. 

VESUV1ANITE 

MgCa5(A10H)Al2(Si04)6 

Dark  brown 
Greenish  brown 
Brownish  yellow 
Greenish  yellow 

Vitreous 
Greasy 

6.5 

7 

GARNET 
var.  Grossularite 
Andradite 
Almandite 
Spessartite 
Pyrope 

Ca3Al2(Si04)3 
Ca3Fe2(Si04)3 
Fe3Al2(Si04)3 
Mn,Al2(Si04)3 
Mg3Al2(Si04)3 

Reddish  brown 
Yellowish  brown 
Reddish  yellow 
Brownish  yellow 

Vitreous 

6.5 
7.5 

TOURMALINE 

7H2O.2Na2O.12MgO.6B2O3.- 
13Al2O324SiO2 

Cinnamon-brown 
Dark  brown 

Vitreous 

Glassy 

7 
7.5 

STAUROLITE 

HFeAl5Si2O13 

Dark    reddish 
brown 

Vitreous 

7 
7.5 

BERYL 

Be3Al2(Si03)6 

Golden  yellow 
Greenish  yellow 

Vitreous 
Glassy 

7.5 

8 

ZIRCON 

ZrSiO4 

Slate-brown 
Light  brown 
Dark  brown 

Vitreous 
Pearly 
Resinous 

7.5 

8 

TOPAZ 

Ala(F,OH)^Oi 

Honey-yellow 
Wine-yellow 
Yellowish  brown 

Vitreous 

8 

PINK,  RED,  OR  RED-VIOLET. 

GYPSUM 

CaS04+2H20 

Brick-red 

Vitreous 
Silky 

1.5 
2 

LEPIDOLITE 

(LijK^L^OH^O, 

Pale  pink  to 
Deep  rose-red 

Pearly 

2.5 
4 

VANADINITE 

(PbCl)Pb4(V04)3 

Bright  red 
Orange-red 
Ruby-red 

Adaman- 
tine 
Greasy 

2.5 
3 

WULFENITE 

PbMoO4 

Orange-red 

Adaman- 
tine 
Greasy 

3 

CALCITE 

CaCO3 

Pink 
Brick-red 

Vitreous 

3 

OR  LIGHT  GRAY. 


System.       Cleavage  or  Fracture. 

G.    1        Common  Structure. 

Observations. 

Tetrag. 

C,  not  prominent 
Brittle 

3.4 

Square  prisms  with 
low  pyramids;  mas- 
sive; granular 

Often  in  white  or  blue 
calcite;  prism  faces  gen- 
erally vertically  striated 

Isom. 

C,  none 
F,  uneven,  coarse 
Brittle 

3.1 
4.3 

Crystals;  dodecahe- 
drons with  icosatet- 
rahedrons  ;  granular  ; 
massive 

Often  in  schists  and 
gneisses;  also  with  cal- 
cite; usually  in  crystals 

Hex. 

C,  none 
F,  uneven 
Very  brittle 

3 
3.2 

Trigonal  ;  prisms 
with  vertically  striat- 
ed faces 

Prisms  usually  much 
cross-fractured;  often  in 
calcite  with  tremolite 

Orth. 

C,  not  important 
F,  uneven 
Brittle 

3.7 

Crystals  ;  often 
twinned  in  crosses,  or 
X  -shaped 

Usually  in  schists  ;  often 
with  cyanite;  sillimanite 

Hex. 

C,  not  important 
F,  uneven 
Brittle 

2.6 

2.8 

Hexagonal  prisms 
with  base 

Harder  than  quartz, 
and  crystals  have  basal 
planes 

Tetrag. 

C,  none 
F,  conchoidal 
Brittle 

4.7 

Square  prisms  with 
pyramids  ;  rounded 
grains 

Often  in  granitic  rocks; 
crystals  always,  and  usu- 
ally small 

Orth. 

C,  basal,  very  prom- 
inent 
Brittle 

3.4 
3.6 

Crystals  ;  prisms; 
pyramids 

Always  in  crystals  ;  some- 
times in  cavities  in  rhyo- 
lite 

Mono. 

C,  clinopin  a  c  o  i  d  a  1, 
perfect  and  prom- 
inent 
Brittle 

2.3 

Columnar  ;  fibrous  ; 
massive;  granular 

Gypsum  stained  by  fer- 
ric oxide 

Mono. 

C,  basal,  perfect    and 
prominent 
Tough 

2.9 

Micaceous;  flakes; 
scales;  compact  scaly 
masses 

Usually  with  rose-red 
tourmaline,  feldspar,  or 
quartz 

Hex. 

C,  not  important 
Brittle 

6.6 
7.2 

Small    hexagonal 
prisms 

Often  with  wulfenite  or 
galenite 

Tetrag. 

C,  not  important 
Brittle 

6.7 

7 

Square  tabular  crys- 
tals 

Often  with  vanadinite 

Hex. 

C,  rhombohedral, 
prominent 
Brittle 

27 

Rhombo  he  d  r  o  n  s  ; 
stalactites;  massive 

Color  due  to  stain  of  fer- 
ric oxide  or  manganese 
oxide 

40 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition  . 

Color. 

Luster. 

H. 

1 

2 

s 

3S 

s 

£ 

3J 
*f 

3 

2 
§ 

D 

5 

HEULANDITE 

H4CaAl2(Si6O18)+3H2O 

Deep  brick-red 

Pearly 

3.5 
4 

SPHALERITE 

ZnS 

v 

Brownish  red 
Yellowish  red 

Resinous 

3.5 
4 

DOLOMITE 

(Ca,Mg)C03 

Pale  pink 

Vitreous 

3.5 
4 

RHODOCHROSITE 

MnCO3 

Rose-red 

Vitreous 

3.5 
4.5 

MARGARITE 

H2CaAl4Si2012 

Pink 
Rose-red 

Pearly 
Vitreous 

3.5 
4.5 

FLUORITE 

CaF2 

Violet-red 
Purple 
Pink 
Amethystine 

Vitreous 
Glassy 

4 

CHABAZITE 

Ca3Ale(SiO<)3(Si308)3 
+  18H2O 

Pale  brick-red 
Flesh-red 

Vitreous 

4 
5 

APOPHYLLITB 

Ht2Ca2(CaOF)2(Si207)3 

Pale  violet-red 

Vitreous 
-Pearly 

4.5 
5 

SCAPOLITE 

WERNERITE 

Ca.AleSieO^ 
with 
Na4Al3ClSi9O24 

Lilac-red 
Violet-red 
Pink 

Vitreous 
Greasy 

5.5 

RHODONITE 

MnSiO3 

Rose-red 
Brownish  red 

Vitreous 

5.5 
6.5 

OPAL 

SiO2+  nH2O 

Brownish  red 

Waxy 

5.5 
6.5 

OR  LIGHT  GRAY. 


41 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Mono. 

C,  clinopinacoidal, 
prominent 
Brittle 

2.2 

Tabular  plates  ;  crys- 
tals 

Often  in  cavities  of  lava 
rock   with    stilbite,    chab- 
azite,  analcite 

Isoni. 

C,  dodecahedral, 
very  prominent 
Brittle 

3.9 
4.1 

Crystals;  massive 

Cleavage  masses  com- 
mon; occurs  with  various 
sulphides 

Hex. 

C,  rhombohedral, 
not    usually 
prominent 
Brittle 

2.9 

Rhombohedrons; 
with     curved    faces; 
saddle-shaped     crys- 
tals 

Often  with  galenite,  cal- 
cite  quartz,  chalcopyrite 

Hex. 

G,  rhombohedral, 
very  prominent 
Brittle 

3.4 
3.6 

Rhombohedrons; 
massive 

Often  with  silver  ores, 
also  quartz,  galenite,  py- 
rite 

Mono. 

C,  basal,   perfect 
and  prominent 
Brittle 

3 

Micaceous;  foliated 

Often  as  Veins  in  green 
chlorite  with  diaspore, 
corundum  ;  not  elastic 
like  muscovite  ;  called 
brittle  mica 

Isom. 

C,  octahedral,    per- 
fect and  prom- 
inent 
Brittle 

3 
3.2 

Cubes;  massive 

Often  with  cassiterite, 
wolframite,  galenite,  py- 
rite 

Hex. 

C,  not  prominent 
F,  uneven 
Brittle 

2 

Crystals;     rhombo- 
hedrons 

Crystals  almost  cubes  in 
shape;  often  with  stilbite 
and  heulandite  in  cavities 
in  lava 

Tetrag. 

C,  basal,  perfect 
and  prominent 
Brittle 

2.4 

Square  prisms  with 
base;  resemble  cubes 

Prism  faces  vertically 
striated;  basal  planes  have 
very  pearly  luster 

Tetrag. 

C,  not  prominent 
Brittle 

2.6 

2.8 

Massive  ;    coarse 
granular 

Harder  than  fluorite 

Trie. 

C,  prismatic,  prom- 
inent 
Tough 

3.4 
3.6 

Massive      granular; 
crystals 

Often  in  calcite  with 
franklinite;  also  with  sil- 
ver ores 

Amorph. 

C,  none 
F,  conchoidal, 
prominent 

1.9 
2.3 

Colloidal  masses 

Conchoidal  fracture  char- 
acteristic; softer  than  jas- 
per 

42 


STREAK  UNOOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

ORTHOCLASE 

KAlSi3O8 

Brick-red 
Flesh-red 

Vitreous 
Pearly 

6 
6.5 

ZOISITE 

var.  Thulite 

CajjAl^AlOHXSiOJa 

Bright  rose-red 

Vitreous 

6 
6.5 

CHONDRODITB 

Mg3[Mg(F,OH)2](Si04)2 

Dark  red 
Brownish  red 

Vitreous 

6 
6.5 

RUTILE 

Ti02 

Dark  red 

Adaman- 
tine 

6 
6.5 

ED-VIOLB 

QUARTZ 

var.  Amethyst 
Rose 
Ferruginous 

SiO2 

Amethystine 
Rose-red 
Brick-red 
Violet-red 

Vitreous 
Glassy 
Greasy 

7 

H 

8 

0" 

CHALCEDONY 

var.  Agate 
Carnelian 
Jasper 

SiO2 

Bright  red 
Carnelian-red 
Dark  red 
Brownish  red 

Waxy 
Vitreous 

7 

« 

i 

GARNET 
var.  Grossularite  / 
Essonite        f 
Andradite 
Pyrope 
Almandite 
Spessartite 

Ca3Al2(Si04)3 

Ca3Fe2(Si04)3 
Mg3(Fe,Al)2(Si04)3 
(Mg,Fe)3(Fe,Al)2(SiO<)3 
Mn3(Fe,Al)2(Si04)3 

Light    to   dark 
red 
Brownish  red 
Cinnamon-red 
Rose-red 

Vitreous 

6.5 
7.5 

8 

TOURMALINE 

H8(Na,Li)4Al10B6Si12Oo3 

Pink 
Rose-red 

Vitreous 

Glassy 

7 
7.5 

ANDALUSITE 

Al^SiOg 

Pink 
Pale  rose 

Vitreous 

7 
7.5 

STAUROLITE 

HFeAl5Si2O13 

Dark      brownish 
red 

Vitreous 

7 
7.5 

SPINEL 

MgAl204 

Ruby-red 

Vitreous 

8 

OR  LIGHT  GRAY. 


43 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Mono. 

C,  basal  and  clino- 
pinacoidal, 
prominent 

2.6 

Crystals;  massive 

Occurs  with  quartz,  mica, 
hornblende  in  red  granite  ; 
see  feldspar 

Orth. 

C,brachypinacoidal, 
not  prominent 
Brittle 

3.3 

Massive 

Not  common  color 

Mono. 

C,  not  prominent 
F,  uneven 
Brittle 

3.2 

Crystals;  embedded 
grains 

Occurs  with  spinel  in 
crystalline  limestone  ;  of- 
ten with  chlorite 

Tetrag. 
Hex. 

C,  not  prominent 
F,  uneven 
Brittle 

4.2 

Crystals;  long  slen- 
der prisms;  acicular 

Often  as  acicular  crys- 
tals in  quartz 

C,  none 
F,  conchoidal, 
prominent 
Brittle 

2.6 

Hexagonal  prisms 
and  pyramids;  mas- 
sive 

Ferruginous  quartz  usu- 
ally with  specular  hema- 
tite; rose  quartz  usually 
massive;  amethyst  usual- 
ly in  crystals 

Hex. 

C,  none 
F,  c  o  n  c  h  oi  d  a  1  , 
prominent 
Brittle  to  tough 

2.6 

Massive;  crypto- 
crystalUne;  banded 

Very  common  as  jas- 
per; agate  usually  finely 
banded 

Isom. 

C,  not  prominent 
F,  uneven 
Brittle 

3.1 
4.3 

Crystals  ;  granular  ; 
rounded  grains  ;  mas- 
sive 

Common  in  schists, 
gneisses,  and  crystalline 
limestone 

Hex. 

C,  none 
F,  uneven 
Very  brittle 

3 
3.2 

Prismatic,  often  ra- 
diate or  divergent  ; 
long  trigonal  prisms 

Usually  in  lepidolite  ; 
crystals  often  parti-col- 
ored red  and  green 

Orth. 

C,  not  prominent 
Brittle 

3.2 

Crystals  ;  nearly 
square  prisms;  mas- 
sive 

Often  in  schists  with 
albite,  staurolite 

Orth. 

C,  imperfect 
Brittle 

3.7 

Crystals;    often 
twinned    into   crosses 
and  X  shapes 
/ 

Occurs  in  schists  with 
cyanite,  sillimanite,  an- 
ctalusite,  chlorite 

Isom 

C,  imperfect 
Brittle 

3.5 
4.1 

Rounded  grains; 
small  octahedrons 

Resembles  red  garnet  and 
ruby  corundum 

44 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

TOPAZ 

Al2(F,OH)2SiO4 

Pink 

Vitreous 

8 

CORUNDUM 

A1203 

Ruby-red 

Vitreous 

9 

COLOR  BLUB  OR  BLUE-VIOLET. 

VIVIANITE 

Fe3P208+8H20 

Greenish  blue 
Indigo-blue 

Vitreous 
Pearly 
Dull 

1.5 
2 

CHALCANTHITE 

CuSO4+5H2O 

Sky-blue 
Greenish  blue 

Vitreous 

2.5 

CHRYSOCOLLA 

CuSiO3+2H?O 

Greenish  blue 

Greasy 
Vitreous 
Dull 

2 
4 

CALCITE 

CaCO3 

Sky-blue 

Vitreous 

3 

CELESTITE 

SrSO4 

Light  sky-blue 

Vitreous 

3 
3.5 

BARITE 

BaSO4 

Pale  greenish 
blue 

Vitreous 

2.5 
3.5 

FLUORITE 

CaF8 

Violet-blue 
Greenish  blue 

Vitreous 
Very 
glassy 

4 

CALAMINE 

H2Z%Si05 

Pale  blue 

Vitreous 
Silky 

4.5 
5 

LAZULITE 

MgAl2P209+H20 

Smalt-blue 
Sky-blue 
Azure-blue 

Vitreous 

5 
6 

LAZURITE 
(Lapis  Lazuli) 

Na4(AlS3Na)Ala(SiO4)3 

Deep  azure-blue 
Berlin  blue 
Ultramarine  blue 

Vitreous 

5 
5.5 

OR  LIGHT  GRAY. 


45 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  basal,  very  per- 
fect and  prom- 
inent 
Brittle 

3.4 
3.6 

Crystals 

Usually  artificially  col- 
ored ;  uncommon  color  in 
nature 

Hex. 

C,  rhombohedral, 
not  prominent 
Brittle  to  tough 

3.9 
4.1 

Crystals;   grains; 
massive 

Often  intermixed  with 
blue  when  massive;  very 
hard 

Mono. 

C,  pinacoidal, 
prominent  in 
crystals 

2.6 

Long       prisms; 
fibrous;  earthy 

Earthy  globular  masses 
in  clay  or  rock,  common; 
prisms  in  pyrrhotite  cavi- 
ties 

Trie. 

C,  not  prominent 
F,  conchoidal 
Brittle 

2.1 
2.3 

Crystals  ;     massive  ; 
stalactitic;   fibrous 

Taste  metallic,  nauseous; 
artificial  crystals  common 
as  blue  vitriol 

Amorph. 

C,  none 
F,  conchoidal 
Sectile 

2 
2.2 

Granular;       stains; 
incrustations;    seams 

Often  with  clay,  chal- 
copyrite,  limonite,  mala- 
chite 

Hex. 

C,  rhombohedral, 
very  prominent 
Brittle" 

2.7 

Coarsely     granular  ; 
c,oarse  cleavage  masses 

Often  with  vesuvianite, 
pyroxene 

Orth. 

C,  basal   and  pris- 
matic,    promi- 
nent 

3.9 

Massive;  fibrous 

Massive  varieties  show 
good  cleavage  and  are  al- 
most colorless  ;  heavy 

Orth. 

C,  not  prominent 
F,  fibrous 

4.3 
4.6 

Fibrous 

Heavy  fibrous  mineral 

Isom. 

C,  octahedral,  very 
prominent 
Brittle 

3 
3.2 

Cubes;   compact  or 
granular;    massive 

Usually  violet-blue  or 
greenish  blue;  often  with 
galena,  cassiterite 

Orth. 

C,  prismatic,  some- 
times prominent 
Brittle 

3.5 

Drus}'    crystals; 
coatings',  massive 

Geodal  -  shaped  masses 
with  drusy  surface 

Mono. 

C,  not  prominent  . 
F,  uneven 
Britile 

3 

Crystals;     acute 
pointed  pyramids 

Usually  as  crystals  in 
white  quartzite  rock 

Isom. 

C,  not  prominent 
Brittle 

2.4 

Massive 

Usually  intermixed  with 
calcite  and  pyrite 

46 


STREAK  UNCOLORED,  WHITE, 


Name, 

Composition. 

Color. 

Luster. 

Ho 

COLOR  BLUE  OR  BLUE-VIOLET. 

SODALITB 

Na»(Al,Cl)Al£iAi 

Lavender-blue 
Azure-blue 

Vitreous 
Greasy 

5.5 
6 

OPAL 

SiO2+nH2O 

Pale  grayish  blue 
Greenish  blue 

Waxy 
Vitreous 

5.5 
6.5 

CYANITE 

Al-jSiOt 

Sky-blue 
Pale  greenish  blue 

Vitreous 
Pearly 

5 
7 

TURQUOIS 

A1PO4A1(OH)1+H,O 

Greenish  blue 

Dull 
Waxy 

6 

QUARTZ 

SiO2 

Grayish  blue 
Greenish  blue 

Vitreous 
Glassy 

7 

CHALCEDONY 

Si08 

Grayish  blue 
Greenish  blue 

Waxy 
Greasy 

7 

CORDIERITB 

(lolite) 

Al<JMg4(A10H)2(Si207)5 

Grayish  blue 
Greenish  blue 
Smoky  blue 

Vitreous 

Glassy. 

7 
7.5 

BERYL 

Be3Al2(Si04)6 

Aquamarine  blue 
Pale  blue 
Sky-blue 

Vitreous 
Glassy, 

7.5 

8 

TOPAZ 

Al2(F,OH)2SiO4 

Greenish  blue 
Sky-blue 

Vitreous 

8 

CORUNDUM 

A1203 

Grayish  blue 
Sapphire-blue 

Vitreous 

9 

COLOR  GREEN.  1 

TALC 

H2Mg2(Si03)4 

Pate  green 
Deep  green 

Greasy 

1 
1.5 

VlVIANITE 

Fe3P208-t-8H20 

Bluish  green 

Vitreous 
Pearly 
Dull 

1.5 
2 

OR  LIGHT  GRAY. 


47 


System. 

Cleavage  or  Fracture. 

G. 

Commo'n  Structure. 

Observations. 

Isom. 

C,  dodecahedral, 
not  prominent 
Brittle 

2.1 
2.5 

Massive;   grains 

Usually  with  nepheliter 
leucite  and  albite  in  syen- 
ite rock 

Amorph. 

C,  none 
F,  conchoidal,  prom- 
inent 

1.9 
2.3 

Massive 

Color  not  usually  homo- 
geneous 

Trie. 

C,  pinacoidal,  prom- 
inent 
Tough 

3.6 

Bladed;  reticulated 

Cleavage  faces  usually 
wavy  or  bent  and  with 
much  cross  parting;  often 
in  schists  with  staurolite 

None. 

C,  none 
F,  uneven 

2.6 

Irregular  -shaped 
masses  ;  grams  ;  seams  ; 
impalpable 

Occurs  intermixed  with 
rock  in  veins,  seams,  etc. 

Hex. 

C,  none 
F,  conchoidal     and 
prominent 

2.6 

Crystals;  massive 

Much  more  glassy  and 
crystalline  than  chalced- 
ony 

Hex. 

C,  none 
F,  conchoidal, 
prominent 

2.6 

Geodes;  botryoidal; 
banded;  stalactitic 

Geodes  often  have  glassy 
quartz  centers 

Orth. 

C,  not  important 
F,  uneven 
Brittle 

2.6 

Massive  ;  granular 

Occurs  in  gneisses  '  and 
schists  with  sillimanite, 
andalusite;  resembles  blue 
quartz 

Hex. 

C,  rough  basal 
F,  uneven 
Brittle 

2.6 

2.8 

Hexagonal    prisms  ; 
broken  crystals 

Occurs  in  granite  with 
quartz,  feldspar,  and  mica 

Orth. 

C,  basal,  perfect  and 
prominent 
Brittle 

3.4 
3.6 

Crystals 

Resembles  aquamarine 
beryl  except  in  crystal 
form;  not  common  color 

Hex. 

C,  rhomboTi  e  d  r  a  1  , 
prominent 
Tough 

3.9 
4.1 

Massive  ;   grains; 
barrel-shaped  crystals 

Masses  often  show  fine 
parallel  striations  due  to 
twinning  and  cleavage 

Orth. 

C,  basal,  perfect  and 
prominent 
F,  splintery,  uneven 

2.8 

Foliated  massive 

Soft  and  greasy  feel; 
very  flexible  but  not  elas- 
tic 

Mono. 

C,  clinopinacoidal, 
prominent      in 
crystals 
Brittle 

2.6 

Long    prisms    with 
striated  faces;  earthy; 
powder 

Earthy  masses  in  clay, 
bones,  fossils  ;  crystals 
often  in  pyrrhotite 

48 


STREAK  UNCOLORED,  WHITE, 


Name.                                    Composition.                                 Color. 

Luster. 

H. 

COLOR  GREEtf. 

GARNIERITE 

. 
H3(Ni,Mg)Si04+H20 

Apple-green 

Dull 

1 
2 

CHLORITE 

PROCHLORITE 
CLINOCHLORE 

H8(Mg,Fe)5Al^i3Ol8 

Grass-green 
Brownish  green 
Dark  green 

Pearly 
Vitreous 

1.5 
2.5 

MUSCOVITE 
(Chrome  mica) 

H2KAl3(SiO4)3  with  Cr 

Emerald-green 
Apple-green 

Pearly 
Vitreous 

9 

2.5 

BIOTITE 

(HK)2(Mg,Fe)2(AlFe)2- 
(Si04)s 

Brownish  green 
Deep  green 

Pearly 
Vitreous 

2.5 
3 

CHALCANTHITE 

CuSO4+5H2O 

Bluish  green 

Vitreous 
Greasy 

2.5 

CHRYSOCOLLA 

CuSiO3+2H2O 

Bluish  green 

Greasy 
Vitreous 
Dull 

2 
4 

SERPENTINE 

CHRYSOTILE 
ASBESTOS 

H4Mg3Si209 

Oil-green 
Light  green 
Dark  green 
Blackish  green 

Greasy 
Silky' 

2.5 
4 

ACTINOLITE 

Ca(Mg,Fe)3(Si03)4 

Grass-green 
Deep  green 

Vitreous 
Silky 

2.5 
4 

BARITE 

BaSO4 

Pale  green 

Vitreous 
Glassy 

2.5 
3.5 

WAVELLITE 

A15(OH)3CP04)2+5H02 

Pale  green 
Bright  green 

Vitreous 
Pearly 

3 
4 

PYROMORPHITE 

(PbCl)Pb4(P04)3 

Yellowish  green 
Dark  green 

Adaman- 
tine 
Pearly 

3.5 
4 

FLUORITE 

CaF2 

Pale  green 
Bright  green 
Bluish  green 

Vitreous 
Glassy 

4 

OR  LIGHT  GRAY. 


49 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Amorph. 

C,  none 
F,  earthy 

2.3 

2.8 

Friable  masses  ;  clay- 
like  masses 

Rounded  and  pod-shaped 
masses  in  clay 

Mono. 

C,  basal,  perfect  and 
prominent 
Tough 

2.8 

2.7 
3 

Foliated;  mica- 
ceous; ssaly;  flaky 

Flexible  but  not  elastic; 
dark-colored  in  thin  plates; 
very  common  in  schists 

Mono. 

C,  basal,  perfect  and 
prominent 
Tough 

Micaceous;  scales; 
flakes;  sheets 

Light  color  to  colorless 
in  thin  sheets;  highly 
elastic 

Mono. 

C,  basal,  perfect  and 
prominent 
Tough 

2.7 
3.1 

Micaceous;  scales; 
flakes 

Dark  colored  mica  in< 
thinnest  sheets;  elastic 
and  flexible 

Trie. 

C,  not  prominent 
F,  conchoidal 
Brittle 

2.1 
2.3 

Crystals;  massive; 
fibrous 

Taste  nauseous  metal- 
lic; blue  vitriol 

Amorph. 

C,  none 
F,  conchoidal 
Sectile  to  brittle 

2 
2.2 

Incrustations  ; 
seams;  stains 

Never  fibrous  like  mala- 
chite; often  with  mala- 
chite, chalcopyrite 

Mono. 

C,  not  important 
F,    conchoidal     or 
splintery 

2.6 

Massive  ;    fibrous 

Feels  smooth  and  looks 
greasy  ;  dark  masses  often 
intersected  by  veinlets  of 
chrysotile  asbestos 

Mono. 

C,  fibrous 
Brittle 

3 

Fibrous  reticulated 
masses 

Occurs  as  actinolite 
schists;  individual  fibers 
are  harder 

Orth. 

C,  basal   and    pris- 
m  a  t  i  c  ,     very 
prominent 
Brittle 

4.3 
4.6 

Platy;  massive  ; 
crystals 

Usually  nearly  colorless 
with  greenish  cast;  heavy 
vitreous  mineral 

Orth. 

C,  not  prominent 
Brittle 

2.3 

Fine  radiating 
fibrous  globules; 
rosette-like 

Usually  on  rock  surface 
as  small  fibrous  rosettes 

Hex. 

C,  not  prominent 
Brittle 

6.5 
7.1 

Hexagonal  prisms 
with  striated  faces; 
granular  ;  fibrous 

Often  with  galena,  angle- 
site,  mimetite 

Isom. 

C,  octahedral,  very 
prominent 
Brittle 

3 
3.2 

Cubes  ;  octahedral 
cleavage  pieces;  mas- 
sive; granular 

Often  with  calcite,  ga- 
lena, pyrite,  dolomite 

50 


STREAK  UNCOLORED,  WHITE, 


COLOR  GREEN.  | 

Name. 

Composition. 

Color. 

Luster. 

H. 

CALAMINE 

H2Zn2SiO5 

Bluish  green 
Pale  green 

Vitreous 

4.5 

5 

SMITHSONITE 

ZnCO3 

Grayish  green 
Bluish  green 

Vitreous 

5 

APATITE 

(CaF)Ca4(P04)s 

Pale  green 
Grass-green 
Dark  green 
Brownish  green 

Greasy 
Vitreous 

5 

OPAL 

SiO2+  nH2O 

Grayish  green 

Waxy 
Vitreous 

5.5 

6.5 

WILLEMITE 

Zn2SiO4 

Yellowish  green 
Bright  green 

Vitreous 

5.5 

CYANITE 

Al2SiO5 

Pale  bluish  green 

Vitreous 

5 

7 

g 

0 

PH 

£ 

H 

1 

ffl 

PH 
^ 

ENSTATITE 

MgSiO3 

Grayish  green 
Brownish  green 

Vitreous 
Pearly 

Silky 

5.5 

DIOPSIDE 

CaMg(Si03)2 

Pale  green 
Bright  green 

Vitreous 
Glassy 

5 
6.5 

5 

6 

AUGITE 

Silicate  of  Ca,  Mg,  Fe, 
and  Al,  chiefly 

Blackish  green 

Vitreous 

ACTINOLITE 

Ca(Mg,Fe)3(Si03)4 

Grass-green 
Dark  green 

Vitreous 
Silky 

5 
6 

HORNBLENDE 

Silicate  of  Ca,  Mg,  Fe, 
and  Al,  chiefly 

Blackish  green 

Vitreous 
Pearly 

5 
6 

TURQUOIS 

(Variscite) 

A1PO4A1(OH)3+H2O 

Bluish  green 
Apple-green 

Waxy 
Dull 

6 

OR  LIGHT  GRAY. 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  prismatic,  some- 
times prominent 

3.5 

Fibrous       mammil- 
lary  masses 

Often  with  smithsonite 

Hex. 

C,    rhombodehral, 
not  usually 
prominent 
Brittle    . 

4.4 

Drusy  masses;  bot- 
ryoidal  or  mammillary 

Usually  very  compact, 
like  chalcedony 

Hex. 

C,  basal,  not  prom- 
inent 
Brittle 

3.2 

Hexagonal    prisms  ; 
granular;  massive 

Commonly  intermixed 
with  brown  colors;  often 
withcalcite;  crystals  often 
have  fused  appearance 

Amorph. 

C,  none 
F,  conchoidal     and 
prominent 

1.9 
2.3 

Colloidal  masses 

Waxy  luster  character- 
istic 

Hex. 

C,    prismatic,    not 
prominent 
Brittle 

3.9 
4.1 

Massive;  granular 

Usually  with  franklinite, 
zincite,  and  calcite 

Trie. 

C,  macropinacoidal, 
prominent 
Tough 

3.6 

Bladed;  columnar 

Divergent  columnar;  long 
blades  usually  bent  and 
cross-fractured 

Orth. 

C,  prismatic,  prom- 
inent 
Brittle 

3.1 
3.3 

Prismatic      masses; 
divergent  columns 

Often  much  softer,  owing 
to  alteration  to  serpentine 

Mono. 

C,    prismatic,    not 
prominent 
Brittle 

3.3 

Crystals^        square 
prisms   with   oblique 
base 

Usually  prisms  have  a 
prominent  oasal  parting 

Mono. 

C,    prismatic,    not 
prominent 
Cleavage  angle  =  87° 

3.3 

Crystals;  massive 

Cleavage  not  so  promi- 
nent as  in  hornblende; 
more  common  as  crystals 

Mono. 

C,  prismatic,  prom- 
inent 
Cleavage  angle  = 
124° 

3 
3.2 

Divergent  columnar 
or  fibrous;  reticulated 
masses 

Often  with  talc  or  chlo- 
rite; fine  to  coarse  fibrous 
and  reticulated;  often  in 
schists 

Mono. 

C,    prismatic     and 
very  prominent 
Cleavage  a  n  g  1  e  = 
124° 

3 
3.2 

Massive;  prismatic; 
columnar 

Cleavage  faces  usually 
have  fibrous  appearance  ; 
common  in  granitic  rocks 
and  schists 

None. 

C,  none 
Brittle 

2.6 

Globular  masses: 
veins;  seams 

Usually  intermixed  with 
rock  in  irregular  masses  or 
veins 

52 


STREAK  UNCOLORED,  WHITE, 


COLOR  GREEN. 

Name. 

Composition. 

Color. 

Luster. 

H. 

NEPHELITE 
(Elaeolite) 

NaAlSiO4 

Grayish  green 
Brownish  green 

Greasy 
Vitreous 

5.5 

6 

MICROCLINE 

(Feldspar) 

KAl.Si3O8 

Bright  green 

Vitreous 
Pearly 

6 
6.5 

PREHNITE 

H2Ca2Al2(SiO4)8 

Pale  green 
Bright  green 

Vitreous 

6 
6.5 

CHLORITOID 

H2(Fe,Mg)Al2Si07 

Dark  green 
Greenish  black 

Pearly 
Vitreous 

6.5 

EPIDOTE 

HCa2(Al,Fe)3Si3013 

Pistachio-green 
Yellowish  green 
Oil-green 
Brownish  green 

Vitreous 

6 

7 

VESUVIANITE 

MgCa5(Al,OH)Al2(Si04)5 

Brownish  green 
Bright  green 

Vitreous 
Greasy 

6.5 

OLIVINE 

(Chrysolite) 

(Mg,Fe)2Si04 

Bottle-green 
Oil-green 
Grass-green 

Vitreous 

Glassy 

6.5 

7 

JADEITE 

NaAl(SiO3)2 

Grayish  green 
Deep  green 

Vitreous 
Silky 

6.5 

7 

QUARTZ 

SiO2 

Light  to  dark 
green 

Vitreous 

Glassy 

7 

CHALCEDONY 

var.  Jasper 
Chrysoprase 
Plasma 

SiO2 

Apple-green 
Leek-green 
Light  to  dark 
green 

Vitreous 
Waxy 

7 

GARNET 
(Uvarovite) 

Ca,Cr2(SiO.>: 

Emerald-green 

Vitreous 

7 
7.5 

TOURMALINE 

4H2O.2(Na,Li)2O. 
3B2O3.8Al2O3.12SiO2 

Dark  green 

Vitreous 
Glassy 

7 
7.5 

OR  LIGHT  GRAY. 


53 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  not  prominent 
Brittle 

2.6 

Massive  ;  short  hex- 
agonal prisms  (rare) 

Usually  with  augite,  soda- 
lite,  leucite 

Trie. 

C,  basal  and  brachy- 
pinacoidal 
Brittle 

2.5 

Crystals  ;  cleavage 
pieces 

Pearly  luster  on  basal 
cleavage,  also  vein-like 
markings;  green  Amazon 
stone 

Orth. 

C,  not  prominent 
F,  uneven 
Brittle 

2.9 

Reniform  masses 
with  drusy  surfaces; 
small  stalactitic 

Occurs  usually  in  cavi- 
ties and  fissures  in  basalts 
and  diabases 

Mono. 

C,  basal,  prominent 
Brittle 

3.5 

Foliated  massive  ; 
micaceous;  platy 

Deep  green  in  thin  plates; 
resembles  hornblende 

Mono. 

C,  basal,  perfect  and 
usually    promi- 
nent 
Brittle 

3.2 
3.5 

Crystals;  prismatic; 
long  columnar;  gran- 
ular; massive 

Often  in  quartz;  also 
with  pyroxene,  hornblende, 
magnetite,  garnet 

Tetrag. 

C,  not  prominent 
F,  uneven 
Brittle 

3.4 

Square  prisms;  faces 
often  vertically  stri- 
ated; massive;  gran- 
ular 

Often  with  calcite;  crys- 
tals usually  not  perfect 

Orth. 

C,  not  important 
Brittle 

3.3 

Rounded  masses  of 
green  grains  ;  massive 
granular 

Occurs  in  basalt  as  bomb- 
shaped  masses  of  light  and 
dark  green,  very  glassy 
grains 

Mono. 

C,  not  prominent 
Tough 

3.3 

Very  compact 
fibrous 

Tough  masses  of  inter- 
locking fibers 

Hex. 

C,  none 
F,  conchoidal     and 
prominent 

2.6 

Hexagonal  prisms 
and  pyramids 

Quartz  stained  with  chlo- 
rite or  actinolite 

Hex. 

C,  none 
F,  conchoidal     and 
prominent 
Brittle 

2.6 

Massive,  compact; 
cryptocrystalline 

Not  so  glassy  as  quartz 

Isom. 

C,  none 
Brittle 

3.5 

Small  crystals;  gran- 
ular 

Sometimes  on  chromite 
as  green  glassy  crystals 

Hex. 

C,  none 
F,  uneven 
Very  brittle 

3 
3.2 

Trigonal  or  hexag- 
onal prisms 

Often  with  pink  tourma- 
line in  lepidolite  or  with 
quartz,  biotite,  feldspar 

54 


STREAK  UNCOLORED,  WHITE, 


fc 

8 

i 

s 

i 

8 

Name. 

Composition. 

Color. 

Luster. 

H. 

BERYL 

var.  Aquamarine 
Emerald 
Common 

Be3Al2(Si03), 

Pale  green 
Bluish  green 
Sea-green 
Emerald-green 

Vitreous 
Very 
glassy 

7.5 

8 

TOPAZ 

AL^OH^iO, 

Bluish  green 

Vitreous 

8 

CHRYSOBERYL 

BeAlA 

Brownish  green 

Greasy 
Vitreous 

8 
8.5 

CORUNDUM 

A1A 

Bluish  green 
Grayish  green 

Vitreous 

9 

BIOTITE 

(Mica) 

(HK)2(Mg,Fe)2(Al,Fe)2- 
(Si04)3 

Brownish  black 
Greenish  black 

Vitreous 
Pearly 

2.5 
3 

CALCITE 
DOLOMITE 
(Limestone) 

CaCO3 
(Ca,Mg)C03 

Grayish  black 

Vitreous 

3 
3.5 
4 

FLUORITE 

CaF2 

Dark  purple- 
black 

Vitreous 

4 

HORNBLENDE 

Silicate  of  Ca,  Mg,  Fe,  and 
Al,  chiefly 

Greenish  black 
Brownish  black 

Vitreous 
Silky 
Pearly 

5 

6 

AUGITE 

Silicate  of  Ca,  Mg,  Fe,  and 
Al,  chiefly 

Greenish  black 
Brownish  black 

Vitreous 

5 

6' 

ALLANITE 

(Ca,Fe)2(Al,Ce,Fe)2- 
(A10H)(Si04)3 

Brownish  black 
Pitch-black 

Pitchlike 
Subme- 
tallic 

5.5 
6 

BROOKITE 

TiO2 

Brownish  black 

Subme- 
tallic 
Adaman- 
tine 

5.5 
6 

OR  LIGHT  GRAY. 


55 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Hex. 

C,  rough  basal,  not 
prominent 
Brittle 

2.6 

2.8 

Hexagonal     prisms 
with  basal  planes; 
broken  crystals 

Often  in  granite  with 
mica  and  feldspar 

Orth. 

C,  basal,  perfect  and 
prominent 
Brittle 

3.4 
3.6 

Crystals 

Often  nearly  square 
prisms  with  base;  resem- 
bles aquamarine  beryl,  ex- 
cept in  form 

Orth. 

C,  not  prominent 
Brittle 

3.5 
3.8 

Twinned     crystals  ; 
tabular 

Plates  with  twinning 
striations  radiating  from 
center;  occurs  with  feld- 
spar, garnet 

Hex. 

C,  rho'mbohedral 
prominent 
Tough 

3.9 
4.1 

Massive 

Often  with  cleavage 
striations  on  faces 

Mono. 

C,  basal,  perfect  and 
prominent 
Tough 

2.7 
3.1 

Micaceous  ;     plates  ; 
scales 

Dark-colored  mica  in 
thinnest  plates;  common 
in  granitic  rocks 

Hex. 

C,  none 
F,  fine     or     coarse 
granular 
Brittle 

2.7 
2.9 

Compact  granular 

Black  limestone  or  mar- 
ble 

Isom. 

C,  octahedral, 
prominent 
Brittle 

3 
3.2 

Massive;  banded 

Black  color  not  common 

Mono. 

C,  prismatic,  prom- 
inent 
Cleavage  angle  124° 

2.9 
3.4 

Massive;       fibrous; 
long  prismatic 

Cleavage  faces  very 
bright  with  often  fibrous 
appearance;  common  with 
feldspar,  quartz 

Mono. 

C,    prismatic,    not 
very  prominent 
Cleavage  angle  87° 

3.3 

Almost   square 
prisms    with    oblique 
bases;  massive 

Usually  with  dark  basal- 
tic rocks;  cleavage  not  so 
good  as  hi  hornblende 

Mono. 

C,  not  prominent 
F,  uneven 
Brittle 

3.5 
4.2 

Tabular      crystals; 
thin  seams  in  rock 

Occurs  in  granitic  rocks 
as  black,  pitch-like  veins 
or  as  crystals 

Orth. 

C,  not  prominent 
Brittle 

3.8 

4.8 

Crystals      only; 
square  or  hexagonal- 
shaped  pyramids 

Crystal  faces  often  stri- 
ated; not  twinned  like 
rutile 

56 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color.  ' 

Luster.          H. 

COLOR  WHITE,  GRAY,  OR  COLORLESS.  |  COLOR  BLACK. 

RUTILE 

TiO2 

Brownish  black 

Metallic 
Adaman- 
tine 

6 
6.5 

CASSITERITE 

SnO2 

Black 

Subme- 
tallic 
Adaman- 
tine 

6 

7 

QUARTZ 

SiO2 

Grayish  black 
Brownish  black 

Vitreous 

7 

GARNET 
var.  Melanite 

Silicate  of  Ca,  Fe,  Al, 
and  Ti 

Velvet-black 
Brownish  black 

Vitreous 
Velvety 

7 
7.5 

TOURMALINE 

Borosilicate  of  Al,  Fe,  and 
Mg 

Coal-black 

Vitreous 
Very 
glassy 

7 
75 

SPINEL 

(Mg,Fe)Al204 

Grayish  black 

Vitreous 
Dull 

8 

ULEXITE 

NaCaB5O9+8H2O 

Snow-white 

Pearly 

Silky 

1 

TALC 

Soapstone 

H2Mg2(Si03)4 

White  " 
Greenish  white 
Gray 

Pearly 
Greasy 
Dull 

1 

15 

PYROPHYLLITE 

HAl(Si03)2 

White 
Grayish 
Brownish  gray 

Pearl  v 
Greasy 
Dull 

1 
2 

CERARGYRITE 
(Hornsilver) 

AgCl 

Gray 
Brownish  gray 

Resinous 
Waxy 

] 
15 

SAL  AMMONIAC 

NH4C1 

White 
Gray 
Colorless 

Vitreous 

1.5 
2 

CALCITE 
var.  Chalk 

CaCO3 

White 

Earthy 
Dull 

1.5 
2.5 

OR  LIGHT  GRAY. 


57 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure 

Observations. 

Tetrag. 

C,  not  prominent 
Brittle 

42 

< 
Crystals,    usually 
twinned     and     faces 
deeply  striated 

Crystals  generally  imper- 
fect ;  knee-shaped  twins 
common 

Tetrag. 

C,  not  prominent 
F,  uneven,  coarse 
Brittle 

68 
7.1 

Massi  ve  ;  granular  ; 
rolled  pe  bbles  ; 
twinned  crystals 

Often  with  quartz,  mica, 
wolframite,  fluorite;  heavy 
black  masses 

Hex. 

C,  none 
F,  conchoidal 
Brittle 

26 

Crystals;  hexagonal 
prisms  and  pyramids 

Very  dark  smoky  quartz 

Isom. 

C,  none 
F,  uneven 
Brittle 

38 

Crystals  ;  rhombic 
dodecahedrons 

Uncommon  color 

Hex. 

C,  none 
F.  uneven 
Very  brittle 

3 
3.2 

Crystals;  long  trig- 
onal- shaped  prisms  ; 
sometimes  divergent 
columnar 

Crystal  faces  usually  stri- 
ated vertically,  and  much 
fractured  horizon  tally; 
often  as  coal-black  crystals 
in  quartz  and  feldspar 

Isom. 

C,  imperfect 
F,  conchoidal 
Brittle 

3.5 
41 

Crystals;   octahe 
drons 

In  granular  limestone 
often  with  chondrodite 

C,  not  important 
F.  fibrous 

16 

Soft  fibrous  masses 

Usually  in  ball  like 
masses  of  fibers 

Mono 

C,  basal  .  p  e  r  f  e*c  t 
and   prominent 
in  the   foliated 
masses 

28 

Foliated  ;  compact 
massive;  fibrous 

Soft  and  greasy  feel; 
fibers  usually  not  radiate 
like  pyrophyllite 

Mono 

C,  basal  and  prom- 
inent 
Flexible 

2.9 

Fibrous,  radiate; 
foliated;  massive 

Often  in  small  hemi- 
spheres of  radiating  fibers; 
soft  and  greasy  like  talc 

Isom. 

C,  none 
Sectile 

5.5 

Wax-like  crusts; 
horn-like  masses 

Cuts  like  wax;  often  with 
ores  of  silver 

Isom. 

C,  not  important 
Brittle 

1.5 

Crusts;  globular 
masses 

Occurs  on  lava  rock; 
disagreeable  saline  taste 

C,  none 
Brittle 

2.7 

Soft  white  earthy 
masses 

Resembles  white  kao- 
linite,  but  lias  no  clay  odor 

58 


STREAK  UNCOLORED,  WHITE, 


COLOR  WHITE,  GRAY,  OR  COLORLESS.  | 

Name. 

Composition. 

Color. 

Luster. 

H. 

GYPSUM 
var.  Selenite 
Alabaster 
Satin-spar 
Common 

CaS04+2H20 

Colorless 
White 
Gray 

Pearly 
Vitreous 
Silky 
Dull 

1.5 
2 

KAOLINITE 

(Clay) 

E«Al£iA 

White 
Gray 
Colorless 

Dull 
Earthy 
Greasy 

2 
2.5 

BAUXITE 

A12O3+3H2O 

White 
Gray 

Earthy 
Dull 

2 
2.5 

SEPIOLITE 
(Meerschaum) 

H4Mg2Si3Ol0 

White 

Earthy 
Dull 

2 
2.5 

BORAX 

Na2B407+H20 

Snow-white 
Colorless 

Earthy 
Dull 
Vitreous 

2 
2.5 

KALJNITE 
(Alum) 

A1K(SO4)2+1.2H2O 

White 
Colorless 

Vitreous 
Icy 

2.5 

EPSOMITE 

MgS04+7H20 

White 

Vitreous 

2 
2.5 

HALITE 

NaCl 

Colorless 
White 
Bluish  white 

Vitreous 

2.5 

BRUCITE 

Mg(OH)2 

White 
Greenish  white 

Pearly 

2.5 

TREMOLITE 
var.  Asbestos 
Mountain 
leather 
Mountain 
cork 

CaMg3(Si03)4 

White 
Gray        , 

Silky 
Pearly 

2 
2.5 

SERPENTINE 
var,  Chrysotile  or 
Asbestos 

H4Mg3Si209 

Greenish  white 

Silky 

2.5 
4 

OR  LIGHT  GRAY. 


59 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Mono. 

C,  clinopinacoidal, 
prominent    in 
selenite 
Sectile 

2.3 

2.6 

Colorless  crystals 
and  cleavage  plates  ; 
massive  white  ; 
fibrous;  columnar; 
granular 

Soft  and  brittle;  not  so 
pearly  luster  as  brucite, 
and  softer;  compact  trans- 
lucient  masses  common 

Mono. 

C,  basal  in  crystals, 
none  in  massive 
F,  earthy 
Brittle  or  sectile 

Compact      massive  ; 
rarely  in  colorless 
flakes 

Rough  feeling;  soapy 
var  has  greasy  feel;  strong 
odor  of  clay  when  breathed 
on 

C,  none 
F,  earthy 
Brfttle 

2.5 

Compact  massive  ; 
pisolitic 

Distinguished  from  clay 
only  by  pea-shaped  struc- 
ture 

Mono. 

C,   none 
F,  e/rthy 

2 

Massive  ;  mammil- 
lary;  reniform;  very 
compact 

Very  smooth  feel;  has. 
not  the  clav  odor  of  kaolin- 
ite 

Mono. 

C,  orthopinacoidal, 
not  prominent 
Brittle 

1.7 

Crystals;  powder 

Taste  alkaline  ;  white 
crystals  often  have  fresh, 
unaltered  glassy  centers 

Isom. 

C,  none 
Brittle 

1.7 

Crystals;   octahe 
drons  ;  mealy  crusts 

Alum  taste 

Orth. 

C,  brachypinacoid- 
al,  prominent 
Brittle 

1.7 

Long  acicular  crys- 
tals; capillary  tufts; 
efflorescences 

Taste  bittei  and  salt; 
often  5n  sulphide  mines  as 
efflorescences  on  walls 

Isom. 

C,  cubic,  perfect  and 
prominent 
Brittle 

21 
2.6 

Cubes;  massive  ; 
granular 

Salt  taste  :  sometimes 
with  anhydrite 

Hex. 

C,  basal,  perfect  and 
prominent 

Flexible 

« 

2.5 

Foliated;  massive 

Resembles  gypsum  but 
has  more  pearl  v  luster; 
often  with  seipentine  ( 

Mono. 

C.  fibrous 
F,  fibrous 
Brittle 

<1 
3 

Fibrous;  asbesti- 
form;  sheets;  cork- 
like  masses 

Occurs  with  tremolite, 
feldspar  quartz;  not  green 
like  chrysotile  when  com- 
pact 

Mono. 

C,  fibrous 
Brittle 

2.6 

Fibrous;  asbesti- 
form 

Narrow  fibious  veins  in 
serpentine  :  fibers  are  green 
in  compact  mass 

60 


STREAK  UNCOLORED,  WHITE 


Name. 

Composition. 

Color. 

Luster. 

H. 

m 

M 

1 

8 
§ 

5" 
3 

4* 
a 

(3 

§ 

0 

ANDALUSITE 

var.  Chiastolite 

ALjSiOs 

Dark  gray 
Blackish  gray 

Vitreous 

2 
4 

MUSCOVITE 

(Mica) 

H2KAl3(Si04)3 

Colorless 
Gray 

Pearly 
Vitreous 

2 

2.5 

LEPIDOLITE 

(Mica} 

(LHQaAl^OH^iaO, 

Pale  pinkish 
white 
Lavender 
Gray 

Pearly 

2.5 
4 

CRYOLITE 

Na3AlF8 

Pure  white 

Icy 

Vitreous 

2.5 

CALCITE 

var.  Iceland  spar 
Stalactites 
Marble 
Common 

CaC03 

White 
Gray 
Colorless 

Vitreous 

Glassy 

3 

ANGLESITE 

PbSO4 

Gray 
White 
Colorless 

Adaman- 
tine 
Greasy 
Dull 

3 

CERUSSITE 

PbCO3 

Cream-white 
Gray 

Adaman-    3 
tine          3.5 

BARITE 

BaSO4 

White 
Colorless 
Gray 
Yellowish  white 

Vitreous 
Pearly 

2.5 
3.5 

ANHYDRITE 

CaSO4 

White 
Bluish  white 
Reddish  white 
Gray 

Vitreous 
Pearly 

3 
3.5 

CELESTITE 

SrS04 

Colorless  with 
bluish  tinge 
White 

Vitreous 
Glassy 

3 
3.5 

OR  LIGHT  GRAY. 


61 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  not  prominent 
Brittle 

3.2 

Rounded  prisms  ; 
square  prisms 

Occurs  in  schists  often  as 
knotty  projections  ;  end 
sections  show  black  squares 
or  crosses 

Mono. 

C,  basal,  perfect  and 
very  prominent 
Tough 

2.7 
3 

Micaceous;  large 
sheets  ;  foliated; 
flakes;  scales 

Highly  flexible  and  elas- 
tic ;  colorless  in  thin  sheets  ; 
cleavable  In  the  thinnest 
sheets 

Mono 

C,  basal,  perfect  and 
prominent 
Tough 

2.9 

Fine  or  coarse  scaly 
masses;  platy;  mica- 
ceous; foliated 

Compact  scaly  masses 
containing  pink  tourmaline 

Mono. 

C,  basal  and  pina- 
coidal  ;  basal  is 
prominent 

3 

Massive 

S  n  o  w-i  c  e  appearance  ; 
often  with  sidente;  cleav- 
age in  three  directions  al- 
most at  right  angles 

Hex. 

C,  rhomboh  e  d  r  a  1, 
very  perfect 
and  prominent 
Brittle 

2.7 

Crystals;  rhombo- 
hedrons  ;  scalenohe- 
drons;  granular;  stal- 
actitic;  banded,  etc. 

Commonly  assor  i  a  t  e  d 
with  the  metallic  minerals  ;. 
colorless  variety  is  Iceland 
spar;  calcite  is  apt  to  be 
stained  any  color 

Orth. 

C,  not  prominent 
F,  conchoidal 
Brittle 

6.1 
6.3 

Massive,  often  band- 
ed; crystals 

Occurs  with  galena  as  an 
alteration  product  ;  crys- 
tals are  colorless;  gray 
masses  often  have  core  of 
galena 

Orth. 

C,  not  prominent 
Very  brittle 

6.5 

Prismatic  crystals; 
massive 

Occurs  similar  to  angle- 
site;  gray  masses  some- 
what porous  or  reticulated 

Orth. 

C,  basal   and    pris- 
matic,    promi- 
nent 

4.3 
4.6 

Crystals;  crested 
masses;  granular  ; 
lamellar;  concretions 
massive 

Often  with  galena  ;  heavy 
white  mineral,  called  heavy 
spar 

Orth. 

C,  pinacoidal, 
prominent 
Brittle 

3 

Massive  ;  granular  ; 
scaly 

Cleavage  in  three  direc- 
tions at  right  angles,  mak- 
ing cube  forms,  occurs 
with  gypsum,  limestone 

Orth. 

C,  basal   and   pris- 
matic;      basal 
very  prominent 

3.9 

Cleavage  masses  ; 
crystals 

Often  as  colorless  crystals 
with  native  sulphur 

62 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

WITHERITE 

BaCO3 

White 

Vitreous 

3 
3.5 

STRONTIANITE 

SrCO3 

White 
Yellowish  white 

Vitreous 
Glassy 

3 
3.5 

ARAGONITE 

CaCO3 

White 
Gray 
Colorless 

Vitreous 

Glassy 

3.5 
4 

DOLOMITE 

(CaMg)C03 

White 
Gray 

Vitreous 

3.5 
4 

SIDERITE 

Fe003 

• 

Brownish  gray 

Vitreous 
Pearly 

3.5 
4 

4 

FLUORITE 

CaF2 

Greenish  white 
White 
Colorless 

Vitreous 
Glassy 

COLEMANITE 

Ca2B6Ou+5H2O 

Colorless 
White 
Yellowish  white 

Vitreous 
Very 
glassy 

4 
4.5 

SCHEELITE 

CaWO4 

Gray 
Yellowish 

Adaman- 
tine 
Greasy 

f5 
5 

WOLLASTONITE 

CaSiO3 

White 
Gray 

Vitreous 

4.5 
5 

CHABAZITE 

Ca3Alf(Si04)3(Si308)3 
+  18H2O 

White 
Colorless 
Gray 

Vitreous 

4 
5 

APOPHYLLITE 

H7KCa4(SiO3)8+4iH2O 

White 
Colorless 
Yellowish 

Vitreous 
Glassy 
Pearly 
on  base 

4.5 
5 

OR  LIGHT  GRAY. 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,  not  prominent 
Brittle 

4.3 

Columnar;  hexag- 
onal-shaped crystals 
with  striated  faces 

Sometimes  with  galena; 
heavy  snow-white  masses 
common 

Orth. 

C,   prismatic,  some- 
times prominent 
Brittle 

3.7 

Columnar  masses 

Divergent  columnar 
masses  resembling  ara- 
gonite  or  calcite,  but  much 
heavier 

Orth. 

C,  prismatic  but  not 
usually     promi- 
nent 
Brittle 

2.9 

Stalactitic;  banded; 
columnar;  hexagonal- 
shaped  crystals 

Distinguished  from  cal- 
cite by  lack  of  cleavage 
and  by  hardness 

Hex. 

C,  rhombohe  d  r  a  1, 
sometimes 
prominent 
Brittle 

2.9 

Rhombo  h  e  d  r  o  n  s 
with  curved  faces; 
massive  ;  granular 

Massive  variety  indis- 
tinguishable from  calcite 
except  somewhat  harder; 
crystals  have  curved  faces 

Hex. 

C,  rhombohe  d  r  a  1, 
very  prominent 
Brittle 

3.8 

Rhombo  h  e  d  r  o  n  s 
with  curved  faces; 
saddle-shaped  masses; 
compact;  massive 

Darker  and  heavier  than 
dolomite  ;  often  as  rhombo- 
hedrons  in  cryolite 

Isom. 

C,  octahedral,  very 
prominent 
Brittle 

3 
3.2 

Cubes  ;  octahedrons  ; 
massive;  granular 

Often  with  magnetite, 
pyrite,  calcite;  sometimes 
very  compact  granular 

Mono. 

C,  clinopinacoid  a  1, 
very  prominent 
Brittle 

2.4 

Crystals;  massive 

Cleaves  into  thin  brittle 
plates 

Tetrag. 

C,  not  prominent 
Brittle 

5.9 
6.1 

Crystals;  pyramids; 
massive 

Often  with  cassiterite, 
wolframite,  purple  fluorite  ; 
very  heavy 

Mono. 

C,  orthopinacoidal, 
not  prominent 
Brittle 

2.9 

Fibrous;  columnar 

Parallel,  or  reticulated, 
fibrous  masses;  often  in 
marble;  resembles  tremo- 
lite 

Hex. 

C,  not  prominent 
Brittle 

2.1 

Crystals,  almost 
cubic  in  shape 

Usually  in  cavities  of 
lava  rock  with  stilbite, 
heulandite,  natrolite 

Tetrag. 

C,  basal,  perfect  and 
prominent 
Brittle 

2.4 

Crystals;  short 
prisms  with  base  ;  also 
pointed  pyramids 

Basal  cleavage  has  very 
pearly  luster,  prismatic 
faces  glassy  and  vertically 
striated 

64 


STREAK  UNCOLORED,  WHITE, 


j  COLOR  WHITE,  GRAY  OR  COLORLESS. 

Name. 

Composition. 

Color. 

Luster. 

H. 

CALAMINE 

H2Zn2SiO$ 

Colorless 
White 
Gray 

Vitreous 

4.5 
5 

MAGNESITE 

MgC03 

Snow-white 
Gray 

Vitreous 
Dull 

3.5 
4.5 

SMITHSONITE 

ZnCO3 

Bluish  gray 
Yellowish  gray 

Vitreous 

5 

APATITE 

(CaF)Ca3(P04)3 

Colorless 
Gray 

Vitreous 
Greasy 

5 

PECTOLITE 

HNaCa2(Si03)3 

White 

Silky 
Vitreous 

5 

NATROLITE 

H4NaAl2(Si04)3 

White 
Colorless 

Vitreous 

Silky 

5 
5.5 

DATOLITE 

H4Ca(BO)SiO4 

Colorless 
White 

Vitreous 
Glassy 

5 
5.5 

ANALCITE 

Na2Al2(Si03)4.2H20 

Colorless 
White 

Vitreous 
Glassy 

5 
5.5 

OPAL 

SiO2+nH2O 

Gray 
White 

Waxy 
Vitreous 

5.5 
6.5 

SCAPOLITE 

WERNERITB 

Silicate  of  Ca,  Al,  Na, 
andCl 

Gray 
Greenish  gray 
White 

Vitreous 
Silky 

5.5 
6 

LEUCITE 

KAl(SiO3)2 

Gray 
White 

Vitreous 

5.5 
6 

OR  LIGHT  GRAY. 


65 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,    prismatic     and 
prominent 
Brittle 

3.5 

Drusy  coatings  and 
crusts;  small  crystals 

Often  on  yellowish  brown 
earthy  masses,  in  small 
drusy  crystallizations 

Hex. 

C,  rhombohedral  in 
crystals 
F,  conchoidal    and 
prominent 

3.1 

Crystals  rare;  mas- 
sive, impalpable 

Very  compact  tough 
white  masses  with  soiled 
surfaces;  are  apparently 
very  hard 

Hex. 

C,  rhombohe  d  r  a  1, 
but  not  usually 
prominent 
Brittle 

4.3 
4.5 

Botryoidal  crusts  ; 
drusy  crusts 

Often  with  sphalerite  or 
calamine 

Hex. 

C,  basal,  not  prom- 
inent 
Brittle 

3.2 

Crystals  ;  massive 

Common  white  phosphate 
rock;  crystals  are  color- 
less, green  or  brown  usu- 
ally 

Mono. 

C,  not  prominent 
Brittle  to  tough 

2.7 

Fibrous;  divergent, 
radiate,  reticulated 

Long  white  fibers  diver- 
gent to  sharp  points;  also 
compact  fibrous 

Orth. 

C,  prismatic,  prom- 
inent in  coarse 
varieties 
Brittle 

2.2 

Acicular;  coarse; 
columnar;  fibrous 

Often  with  stilbite,  apo- 
phyllite,  analcite,  chaba- 
zite,  in  cavities  of  lava 
rock  / 

Mono. 

C,  none 
F,  uneven 
Brittle 

3 

Crystals  ;  massive  ; 
granular  to  compact 

Small  glassy  crystals  with 
slight  greenish  tint  on  lava 
rock;  massive  white 

Isoni. 

C,  not  prominent 
Brittle 

2.2 

Crystals;  icosatetra- 
hedrons  or  cubes 

Often  in  cavities  of  lava 
with  apophyllite,  natrolite, 
chabazite,  prehnite,  dato- 
lite 

Amorph. 

C,  none 
F,   conchoidal    and 
very  prominent 

1.9 
2.3 

Massive  ;  colloidal  ; 
blebby;  globular 

Wood  opal;  common 
opal 

Tetrag. 

C,  not  prominent 
Brittle 

2.5 

2.8 

Square  prisms  with 
low  pyramidal  ends; 
massive 

Crystals  usually  have 
rough,  uneven  faces  ;  often 
hi  crystalline  limestone 

Tetrag. 

C,  imperfect 
F,  conchoidal 
Brittle 

2.5 

Crystals;  trapead1 
hedrons 

Always  in  crystals;  oc- 
curs in  volcanic  rocks  with 
nenjaettte>  sodalite 

66 


STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

COLOR  WHITE,  GRAY,  OR  COLORLESS. 

ENSTATITE 

MgSiO8 

Greenish  gray 

Pearly 
Vitreous 

5.5 

PYROXENE 

DlOPSIDE 

CaMg(Si03)2 

Colorless 
Yellowish  white 
Greenish  white 

Glassy 
Vitreous 

6 
6.5 

TREMOLITE 

CaMg3(Si03)4 

White 
Gray 

Silky 
Pearly 
Vitreous 

5 
6 

NEPHELITE 

EluEOLITE 

NaAlSiO, 

Greenish  gray 
Brownish  gray 

Greasy        5.5 
Vitreous     6 

AMBLYGONITE 

Li(Al,F)PO4 

White 

Vitreous 

6 

"FELDSPARS 

ORTHOCLASE 

KAlSi,0, 

White 
Gray 
Colorless 

Vitreous 
Pearly 

6 
6.5 

MICROCLINE 

KAlSi3O8 

White 
Gray 
Yellowish 

Vitreous 
Pearly 

6 
6.5 

ALBITE 

NaAlSi3O8 

White 
Colorless 
Gray 

Glassy 
Vitreous 

6 
6.5 

OLIGOCLASE 

NaAlSi3O8+CaAl2Si2O8 

Colorless 
White 

Vitreous 
Glassy 

6 
6.5 

5 

6 

LABRADOR- 
ITE 

_,„„ 

Dark  gray 
Grayish  white 

Vitreous 
Pearly 

ANORTHITE 

CaAlAO, 

White 
Gray 

Vitreous 

6 
6.5 

OR  LIGHT  GRAY. 


67 


System. 

Cleavage  or  Fracture. 

G. 

Common  Structure. 

Observations. 

Orth. 

C,     prismatic    and 
pinacoidal, 
prominent 
Brittle 

3.1 
3.3 

Columnar,  divergent 
masses;  lamellar 

Often  soft  owing  to  alten- 
ation  to  serpentine  ;  cleav- 
age faces  quite  pearly  or 
silky  in  luster 

Mono. 

C,    prismatic,     not 
prominent 
Brittle 

3.3 

Crystals,     almost 
square  or  rounded 

Often  with  blue  calcite, 
brown  tourmaline 

Mono. 

C,  prismatic,  prom- 
inent 
Cleavage  angle  124° 

2.9 
3.1 

Columnar;    fibrous; 
prismatic  crystals 

Often  as  crystals  in  dolo- 
mitic  limestone  or  marble; 
also  as  compact  fibrous 
masses 

Hex. 

C,  not  prominent 
Brittle 

2.6 

Massive;  sometimes 
hexagonal  prisms 

Often  with  sodalite,  al- 
bite,  leucite;  greasy  luster 
characteristic 

Trie. 

C,  basal,  perfect  and 
prominent 
Brittle 

3 

Compact  massive 

Often  with  lepidolite, 
tourmaline 

Mono. 

C,  basal  and  clino- 
pinacoidal, 
prominent 
Brittle 

2.4 
2.6 

Crystals  ;     massive  ; 
cleavage  pieces 

Two  cleavages  at  right 
angles;  common  in  granitic 
rocks  with  mica,  horn- 
blende, and  quartz 

Trie. 

C,  basal  and  brachy- 
pinacoi  d  a  1, 
prominent 

2.5 

Crystals;    massive 

Usually  has  fine  cross- 
veined  structure  on  the 
basal  plane 

Trie. 

C,  basal  and  brachy- 
pinacoidal,   not 
so  prominent 

2.6 

Small    crystals; 
twinned  crystals; 
platy  masses 

Fine  parallel  striations  or 
reentrant  angles  on  the  base 
due  to  twinning 

Trie. 

C,  basal  and  brachy- 
pinacoidal,  not 
so  prominent 

2.6 

Crystals;  massive 

Fine  parallel  striations  on 
the  basal  cleavage  due  to 
twinning 

Trie. 

C,  basal  and  brachy- 
pinacoidal, 
prominent 

2.7 

Massive;      cleavage 
pieces 

Fine  striations  on  basal 
cleavage  due  to  twinning; 
usually  shows  a  beautiful 
play  of  colors;  blue,  green, 
gold,  etc. 

Trie. 

C,  basal,  prominent 
F,  uneven 
Brittle 

2.7 

Crystals;   prismatic 

Occurs  in  volcanic  lavas; 
not  so  common  as  the  other 
feldspars 

STREAK  UNCOLORED,  WHITE, 


Name. 

Composition. 

Color. 

Luster. 

H. 

ZoiSITE 

Ca^^AlOHXSiOJg 

Grayish  white 

Vitreous 

6 

Greenish  gray 

Pearly 

6.5 

SPODUMENE 

LiAl(Si03)2 

Gray 

Vitreous 

6.5 

White 

Pearly 

7 

DIASPORE 

AIO(OH) 

Lavender-gray 
Grayish  white 

Pearly 
Vitreous 

6.5 

7 

Cream  white 

Adaman- 

tine 

aj 

CO 

3 

QUARTZ 
var.  Rock  crystal 
Milky 
Smoky 

SiO2 

Colorless 
White 
Smoky  gray 

Vitreous 
Greasy 

7 

1 

Common 

§ 

CHALCEDONY 
var.  Agate 

SiO2 

Gray 
White 

Waxy 
Vitreous 

7 

8 

Chert 

Flint 

o 

Hornstone 

Siliceous 

3 

sinter 

s 

ANDALUSITE 

(CHIASTOLITE) 

Al2Si06 

Gray 
Reddish  gray 

Vitreous 

7.5 

w 

H 

[ 

3 

LAWSONITE 

H.CaAljjSijjOio 

Bluish  white 

Vitreous 

7.5 

£ 

Gray 

8 

a 

ZIRCON 

ZrSiO4 

Brownish  gray 

Vitreous 

7.5 

8 

Lavender-gray 
Colorless 

Pearly 

8 

TOPAZ 

Al2(F,OH)aSiO4 

White 

Vitreous 

8 

Colorless 

Glassy 

CORUNDUM 

A1203 

Gray 
Bluish  gray 
Greenish  gray 

Vitreous 

9 

DIAMOND 

C 

Colorless 

Adaman- 

10 

Gray 
Yellowish 

tine 

OR  LIGHT 


System. 

~~*pBn 

Cleavage  or  Fracuire^I    G. 

Common  Structure. 

Observations. 

Orth. 

C,  brachypinacoid- 
al  prominent 
Brittle  ' 

3.3 

Columnar;  fibrous; 
prismatic 

Columns  deeply  striated 
vertically,  and  broken 
transversely 

Mono. 

C,  prismatic    often 
prominent 
Brittle 

3.2 

Large  crystals  and 
broad  cleavage  plates 
lamellar 

Often  parts  in  broad 
lamellar  masses 

Orth. 

C,    brachypinacoid 
al  ;    prominent 
Brittle 

3.3 
3.5 

Bladed;  foliated 

Often  as  veins  in  chlorite 
with  margarite,  corundum; 
very  pearly  to  adamantine 
luster 

Hex. 

C,  none 
F,   conchoidal   and 
prominent 
Brittle 

2.6 

Hexagonal  prisms 
and  pyramids;  mas- 
sive; granular;  sand; 
pebbles 

Commonest  mineral;  oc- 
curs in  most  crystalline 
rocks  as  a  constituent  ;  con- 
choidal fracture  is  charac- 
teristic 

Hex. 

C,  none 
F  conchoidal    and 
prominent 
Brittle  to  tough 

2.6 

Geodal;  botryoidal; 
mammillary;  banded; 
concretionary;  mas- 
sive 

Not  glassy  like  quartz; 
cryptocrystalline  in  struc- 
ture ;  banded  varieties 
classed  as  agates;  geodes 
often  have  quartz  centers 

Orth. 

C,  not  prominent 
F,  uneven 
Brittle 

3.2 

Almost    square 
prisms    with    broken 
ends 

End  sections  of  chiasto- 
lite  show  black  crosses  or 
squares  due  to  inclusions 

Orth. 

C,  brachypinacoid- 
al  ;    prominent 
Brittle 

3.1 

Crystals;  lenticular 
plates 

Often  with  margarite, 
actinolite,  chlorite;  resem- 
bles corundum 

Tetrag. 

C,  none 
Brittle 

4.7 

Crystals;  prisms 
and  pyramids 

Occurs  in  granites  and 
syenites;  loose  crystals  in 
gold  sands 

Orth. 

C,  basal,  perfect  and 
prominent 
Brittle 

3.4 
3.6 

Crystals;  white 
massive 

Massive  white  distin- 
guished from  white  quartz 
by  presence  of  cleavage 
faces 

Hex. 

C,  rhombohedral, 
prominent 
Tough 

3.9 
4.1 

Massive  ;     barrel- 
shaped  crystals 

Often  with  chlorite,  mar- 
garite. magnetite  ;  massive  • 
has  usually  fine  parallel 
parting  striations 

Isom. 

C,  octahedral,    not 
•  prominent 
Br'ttle 

3.5 

Small  rounded  octa- 
hedral-shaped crys- 
tals 

Occurs  hi  dark  bluish- 
green  igneous  rock 

OF  THE  X 

UNIVERSITY 


INDEX. 


Actinolite 48,  50 

Agate  36,  42,  68 

Alabandite 28 

Alabaster 58 

Albite 66 

Allanite 36,  54 

Almandite 38,  42 

Alum 58 

Amblygonite 66 

Amethyst  42 

Amphibole 34,50 

Analcite 64 

Andalusite „  42,  60,  68 

Andradite 38,  42 

Anglesite 60 

Anhydrite 60 

Annabergite 26 

Anorthite 66 

Anthophyllite 34 

Antimony 12,  16 

Apatite 32,  50,  64 

Apophyllite 40,  62 

Aquamarine 54 

Aragonite 32,  62 

Argentite 10 

Arsenic 12,  16 

Arsenopyrite 14 

Asbestos 48,  58 

Augite 28,  34,  50,  54 

Axinite 36 

Azurite 26 

Barite 30,44,  48,  60 

Bauxite 18,  24,  28,  58 

Beryl 38,  46,  54 

Biotite 30,  &,  54 

Bismuth 16 

Borax 58 

Bornite 14 

Bronzite 34 


Brookite 24,54 

Brucite 58 

Calamine 32,  44,  50,  64 

Calaverite 16 

Calcite 30,  38,  44,  54,  56,  60 

Carnelian 42 

Cassiterite 22,  26,  36,  56 

Celestite 44,  60 

Cerargyrite 28,  56 

Cerussite 30,  60 

Chabazite 40,  62 

Chalcanthite 44,  48 

Chalcedony 36,  42,  46,  52,  68 

Chalcocite 10 

Chalcopyrite 14 

Chalk 56 

Chert 68 

Chiastolite 60,  68 

Chloanthite 14 

Chlorite 26,  30,  48 

Chloritoid 52 

Chondrodite 36,  42 

Chromite 20,  24 

Chrysoberyl 54 

Chrysocolla 26,  44,  48 

Chrysolite 52 

Chrysoprase 52 

Chrysotile , 48,  58 

Cinnabar 18 

Clay 28,  58 

Clinochlore 26,  30,48 

Cobaltite 14 

Colemanite 62 

Columbite 12,  22 

Copper 18 

Cordierite 46 

Corundum.. . . . 44,  46,  54,  68 

Cryolite 30,  60 

Cuprite 18 

71 


72 


INDEX. 


Cyanite 46,  50 

Datolite 64 

Diamond 

Diaspore 68 

Diopside .  50,  66 

Dolomite 82,  40,  54,  62 

Elaeolite 36,  52,  66 

Emerald 54 

Enargite 10,  14 

Enstatite 34,  50,  66 

Epidote 26,  36,  52 

Epsomite 58 

Erythrite \\     18 

E-ssonite 43 

Famatinite 14 

Feldspar 52,  66 

Fibrolite 36 

Flint . .  36,  68 

Fluorite 32,  40,  44,  48,  54,  62 

Franklinite 12,  20 

Galenite 10   12 

•Garnet. 38,42,  52'  56 

Garnierite 48 

Glaucophane 28 

Gold \     22 

Gothite  or  Goethite 24 

Graphite 10 

Grossularite 38,  42 

Gypsum 28,  38^  58 

Halite 30,  58 

Hematite 18,  20 

Heulandite 40 

Hornblende  / 28,  34,  50,  54 

Hornsilver 56 

Hornstone 68 

Hypersthene 34 

Iceland  spar 60 

Ilmenite 12,  20 

lolite '  46 

Iron , '.[     ]2 

Jadeite  . . . 52 

Jamesonite 10 

Jasper 36,42,  52 

Kalinite 58 

Kaolinite 28,  58 


L,               -          »/     <••  *  -rtvrn. 

abradorite. 66 

Lapis  Lazuli 28,  44 

Lazulite 44 

Lazurite 28,  44 

Lawsonite 68 

Lepidolite 38,  60 

Leucite 64 

Limestone 54 

Limonite 22,  24 

Linarite '  26 

Magnesite. 32,  64 

Magnetite 12 

Malachite 26 

Manganite 20 

Marble 60 

Marcasite 14,  16 

Margarite 40 

Meerschaum 58 

Melanite         56 

Menaccanite 12 

Mercury 16 

Mica 60 

Microcline 52,  66 

Millerite '  14 

Mimetite 30 

Molybdenite 10,  16 

Monazite 34 

Mountain  cork 58 

Mountain  leather 58 

Muscovite. 48,  60 

Natrolite 64 

Nephelite 36,  52,  66 

Niccolite.... 16 

Oligoclase 66 

Oli  vine 52* 

Opal 34,  40,  46,,  50,  64 

Orpiment 22 

Orthoclase 36,  42,  66 

Pectolite 64 

Penninite 30 

Phlogopite 30 

Plasma 52 

Platiniridium 16 

Platinum 16 

Prehnite 52 

Prochlorite 26,  30,  48 

Proustite 18 

Psilomelane , . .      12.  20 


INDEX. 


Pyrargyrite 20 

Pyrite 16 

Pyrolusite 10 

Pyromorphite 24,  26,  30,  48 

Pyrope 38,  42 

Pyrophyllite 56 

Pyroxene 34,  50,  66 

Pyrrhotite 14 

Quartz 36,  42,  46,  52,  56,  68 

Realgar 22 

Rhodochrosite 40 

Rhodonite 40 

Rutile 24,  36,  42,  56 

Sal  Ammoniac 56 

Satin  Spar 58 

Scapolite 40,  64 

Scheelite 32,  62 

Selenite 58 

Sepiolite 58 

Serpentine 30,  48,  58 

Siderite 24,  32,  62 

Siliceous  Sinter 68 

Sillimanite 36 

Silver 16 

Suialtite 14 

Smithsonite 32,  50,  64 

Soapstone 56 

Sodalite 46 

Spessartite 38,  42 

Sphalerite 18,  20,  22,  24,  32,  40 

Spinel 42,  56 

Spodumene 68 

Stalactite 60 

Staurolite 38,  42 

-  Stephanite 10 


PAGE 

Stibnite 10,  12 

Stilbite 32 

Strontianite 62 

Sulphur 22,  28 

Sylvanite 16 

Talc 46,  56 

Tennantite 12 

Tetrahedrite 12,  20 

Thiilite 42 

Titanite 34 

Topaz 38,  44,  46,  54,  68 

Tourmaline 38,  42,  52,  56 

Tremolite 34,  58,  66 

Troostite 34 

Turgite 18 

Turquoise 46,  50 

Ulexite 56 

Uvarovite 52 

Vanadinite 38 

Variscite  50 

Vesuvianite 38,  52 

Vivianite 26,  44,  46 

Wad 18 

Wavellite 48 

Wernerite 40,  64 

Willemite 34,  50 

Witherite 62 

Wolframite 20 

Wollastonite 62 

Wulfenite 30,  38 

Zincite 22 

Zircon 38,  68 

Zoisite 36,  42,  68 


^>    ) 

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M   1935 

MAR  31 19*1 
FEB  7      1955 


i    1954  Lg 
«•  cm  MAR  1 2  1979 


2 
§ 

>. 
,  - 

: 


"-^ 

.. 

3) 


111 
JjJ 

3 


' 


f 


LD  ai-ao/H-b/a-j 


YC   15051 


i 


